The CYP2D6 NM_000106.6:c.506-1G>A (NP_000097.3:p.?) splicing variant has previously been reported in somatic cancers (COSMIC; COSV62243440, n = 12 times). Experimental evidence: The exact variant was reported to cause aberrant 3' splice-site recognition and a predicted frameshift/truncating consequence. Based on available guidelines, this variant is considered to be a Variant of Uncertain Significance (VUS).
Five-step scale from benign to pathogenic. This variant is uncertain. Select a step to read what it means.
This variantScenario
BenignPathogenic
Uncertain.The recorded classification is uncertain significance.
In plain language
Gene-level background from the recorded interpretation.
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About CYP2D6
CYP2D6 encodes a cytochrome P450 enzyme that helps the body process many medicines, including antidepressants, antipsychotics, pain relievers, cough medicines, heart medicines, and anti-nausea drugs. Common genetic differences and changes in gene copy number can make people process these medicines slowly, normally, or very quickly, affecting drug response and side effects. CYP2D6 is not known to have a specific cancer-causing or cancer-protective role.
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01The reasoning
How it was classified
The recorded framework is Generic ACMG/AMP 2015 with ClinGen SVI recommendations. The criteria and strengths shown below come from the saved assessment; this page does not recalculate the classification.
Recorded applied criteria
The applied criteria and their strengths are shown as assessed under the stated framework.
Met, very strong: the canonical -1 splice variant skips 161 coding nucleotides in internal exon 4 of 9, predicting a frameshift subject to nonsense-mediated decay.
PS3Supporting
PS3 · supporting
Met at supporting strength: the exact variant was reported to cause aberrant 3' splice-site recognition and a predicted frameshift/truncating consequence.
Benign criteria applied · 2
BA1Stand alone
BA1 · stand alone
Met: gnomAD v4.1 grpmax FAF is 0.18481171, exceeding the 0.05 BA1 threshold with adequate observed-allele support.
BP4Supporting
BP4 · supporting
Met at supporting strength: SpliceAI maximum delta 0.005 is below the BP4 cutoff of <=0.1 for this canonical splice-site variant.
Recorded classification: Uncertain significance
VUS: PVS1 (very strong) plus PS3 (supporting) satisfy a pathogenic rule, while BA1 (stand-alone benign) satisfies a benign rule under generic ACMG/AMP fallback.
02The sources
Evidence at a glance
Evidence summaries and captured source records, where available. Missing entries should not be interpreted as negative findings.
gnomAD v4.1
gnomAD v2.1
Population frequency
257,187 / 1,578,198 alleles
gnomAD v4.1: 257,187 / 1,578,198 alleles. Recorded AF 0.162962. Recorded homozygote count 9043.
gnomAD v2.1
This variant is present in gnomAD v2.1 (AF= 0.138417; MAF= 13.84168%, 29026/209700 alleles, homozygotes = 2670) and has highest observed frequency in the European (non-Finnish) population (AF= 0.195948; MAF= 19.59479%, 17283/88202 alleles, homozygotes = 1825); grpmax FAF= 0.194193.
ACMG/AMP criteria under Generic ACMG/AMP 2015 with ClinGen SVI recommendations, with the data and sources behind each one.
28 criteria with recorded statuses: 4 met · 5 not met · 11 not assessed · 8 not applicable. Open any row for the full reasoning, the rule and the evidence behind it.
PS2, PM6, PP1, and BS4 are not assessed because the available evidence provides no proband-level de novo documentation, parental testing, pedigree, informative meioses, or affected-relative genotype-phenotype data.
No VCEP covers CYP2D6; generic ACMG/AMP 2015 rules govern.
The reviewed exact-variant literature does not provide PS4 case-control enrichment, and the case evidence lacks the phenotype, family-history, and alternate-molecular-diagnosis facts needed for PP4 or BP5.
ClinVar does not show an exact-variant expert-panel pathogenic or benign classification; single-laboratory and non-expert assertions are excluded from PP5 and BP6 by the specified rules.
The variant is a canonical splice-site/intronic variant; generic PP3 and BP4 therefore use only SpliceAI, with no double-counting of other predictor scores.
SpliceAI maximum delta 0.005 does not meet PP3 but meets BP4 at supporting strength under the supplied generic thresholds.
BA1 is met from the gnomAD v4.1 filtering grpmax FAF of 0.18481171, using the required adequate-allele-count metric rather than a small-subgroup popmax point estimate.
BS1 is not assessed because a disorder-specific maximum credible allele-frequency calculation is unavailable for the common CYP2D6 pharmacogenetic phenotype.
BS2 is not assessed because aggregate homozygote counts do not establish healthy adult status or full early-age penetrance.
PM2 is not met because the variant is common in gnomAD all-comers and non-cancer subsets.
No criteria match.
Met · 4
PVS1Very strongACMG_2015Met, very strong: the canonical -1 splice variant skips 161 coding nucleotides in internal exon 4 of 9, predicting a frameshift subject to nonsense-mediated decay.
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Reasoning
NM_000106.6:c.506-1G>A is a canonical splice-acceptor variant at the -1 position. The affected transcript is the clinically relevant CYP2D6 transcript, and the variant assessment identifies exon 4 of 9 as affected; exon skipping would remove 161 coding nucleotides, which is not divisible by 3 and therefore predicts a frameshift and premature termination. Exon 4 is internal rather than the last or penultimate exon, so the predicted loss-of-function transcript is expected to be subject to nonsense-mediated decay rather than to escape it. The gene-level assessment supports CYP2D6 loss of function as a germline disease mechanism, satisfying the gene eligibility requirement. No named downgrade rule is supported: the affected exon is not a distal terminal exon, no NMD escape is indicated, and no evidence identifies the exon as non-critical or enriched for population loss-of-function variation. The canonical splice-site consequence therefore meets PVS1 at full strength, recorded as the literal strength tier "very strong".
Rule
PVS1: Null variant (nonsense, frameshift, canonical +/−1 or 2 splice sites, initiation codon, single or multi-exon deletion) in a gene where loss of function (LOF) is a known mechanism of disease.
Evidence considered
pvs1_variant_assessment.json, transcript_hgvs NM_000106.6:c.506-1G>A: canonical_splice, canonical_splice_consensus=true, affected exon 4 of 9, exon length 161 coding nucleotides, and exon skipping predicted to shift the reading frame.
pvs1_gene_context.json, gene-level PVS1 eligibility: lof_mechanism_supported=true and pvs1_gene_gate=eligible for CYP2D6.
pvs1_variant_assessment.json, downgrade considerations: the affected exon is neither the last nor penultimate exon, and no NMD escape, non-critical distal exon, or population loss-of-function enrichment is reported.
ClinGen SVI PVS1 recommendations (PMC6185798), cited through source_registry key pvs1_generic_framework, used for the generic PVS1 framework assessment of canonical splice variants and NMD-related downgrade considerations.
PS3SupportingACMG_2015Met at supporting strength: the exact variant was reported to cause aberrant 3' splice-site recognition and a predicted frameshift/truncating consequence.
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Reasoning
PMID:1978565 investigated the exact CYP2D6 intron 3 splice-site variant corresponding to NM_000106.6:c.506-1G>A and reported aberrant 3' splice-site recognition with a downstream frameshift/truncating consequence. This is direct variant-specific functional evidence supporting a damaging effect on CYP2D6 splicing, but the available record does not establish reproducibility in a validated clinical diagnostic laboratory or provide sufficient assay-control detail for a higher strength.
Rule
Well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product.
Evidence considered
Hanioka et al. 1990 (PMID:1978565), paper title: "The human CYP2D locus associated with a common genetic defect in drug oxidation: a G1934----A base change in intron 3 of a mutant CYP2D6 allele results in an aberrant 3' splice recognition site." The case evidence identifies this as the exact c.506-1G>A allele and reports aberrant splice recognition, a single-base deletion, frameshift, and predicted truncated protein.
The evidence is variant-specific and functionally damaging, but the available record does not establish the validated, reproducible clinical-diagnostic-laboratory setting described as the most well-established form of functional evidence.
Still missing
The available record does not document sufficient validated clinical-laboratory reproducibility, independent replication, or complete assay-control details for stronger PS3 calibration.
BA1Stand aloneACMGMet: gnomAD v4.1 grpmax FAF is 0.18481171, exceeding the 0.05 BA1 threshold with adequate observed-allele support.
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Reasoning
BA1 is met under the generic ACMG/AMP threshold. The default all-comers gnomAD v4.1 record is appropriate because no VCEP specifies a non-cancer or exome-only source. The filtering allele frequency, grpmax FAF, is 0.18481171 (18.481171%), well above the 0.05 threshold, and the contributing population data exceed the minimum 2,000 observed-allele requirement. The Amish popmax point estimate of 0.238307 is not used for the decision because its 898 observed alleles are below that minimum; the decision rests on grpmax FAF.
Rule
BA1: Allele frequency is above 5% in Exome Sequencing Project, 1000 Genomes or Exome Aggregation Consortium. ... BA1 (stand-alone): >= 0.05 — ACMG/AMP 2015 stand-alone benign allele frequency (PMID:25741868)
Evidence considered
gnomAD v4.1 all-comers: AF=0.16296244197496132, 257187/1578198 total alleles, 9043 homozygotes, and filtering grpmax FAF=0.18481171.
The highest point estimate is Amish AF=0.2383073496659243 from 214/898 alleles; this small subgroup is not used for BA1 because the observed-allele count is below 2000.
Generic calibration supplied for this case: BA1 stand-alone threshold >=0.05 under ACMG/AMP 2015 (PMID:25741868).
BP4SupportingACMGMet at supporting strength: SpliceAI maximum delta 0.005 is below the BP4 cutoff of <=0.1 for this canonical splice-site variant.
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Reasoning
The variant is a canonical splice-site/intronic variant, so the applicable generic BP4 path is SpliceAI only; REVEL is not applicable. SpliceAI maximum delta is 0.005, which is at or below the supplied BP4 supporting cutoff of <= 0.1, supporting no predicted splice impact at supporting strength. This computational result is not combined with the BayesDel score, which has no established generic ACMG-strength calibration.
Rule
Multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc) ... Intronic, synonymous, or splice-region variant -> SpliceAI only. There is no REVEL score to fall back to. ... BP4 (supporting): <= 0.1 — SpliceAI recommended cutoff (Jaganathan et al. 2019, Cell) (PMID:30661751)
Evidence considered
SpliceAI Lookup reports DS_AG 0.001, DS_AL 0.0, DS_DG 0.0, and DS_DL 0.005; maximum delta = 0.005 for NM_000106.6:c.506-1G>A.
For the generic splice-prediction path, the supplied SpliceAI calibration defines BP4 supporting at <= 0.1 (Jaganathan et al. 2019, Cell, PMID:30661751); the observed maximum delta 0.005 meets this threshold.
The local BayesDel score (-0.0238629) was not used because the supplied governing guidance states that no generic ACMG-strength calibration is established for BayesDel.
PS4ACMG_2015Not met: no variant-specific case-control counts, odds ratio, relative risk, or confidence interval demonstrates the required OR >5.0 with a confidence interval excluding 1.0.
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Reasoning
Generic ACMG/AMP PS4 requires significantly increased prevalence in affected individuals versus controls; the supplied generic note specifies RR or OR >5.0 with a confidence interval that excludes 1.0. The literature packet's only ai_classified_papers entry, PMID:1978565, was verified against its available abstract/title as a functional study of the exact CYP2D6 splice variant in an individual with deficient debrisoquine metabolism, not a case-control comparison. The reviewed paper extracts likewise contain no variant-specific case-control counts, affected-versus-unaffected frequencies, OR, RR, or confidence interval. The available gnomAD frequencies are population data only and cannot establish affected-case enrichment. Therefore PS4 is not met.
Rule
The prevalence of the variant in affected individuals is significantly increased compared to the prevalence in controls. ... Relative risk (RR) or odds ratio (OR), as obtained from case-control studies, is >5.0 and the confidence interval around the estimate of RR or OR does not include 1.0.
Evidence considered
PMID:1978565 title and abstract identify the G1934>A intron-3 CYP2D6 allele corresponding to NM_000106.6:c.506-1G>A and describe an individual deficient in debrisoquine metabolism; they do not report affected-versus-control counts or an association estimate.
PMID:24060820 paper extract: the meta-analysis concerns CYP2D6 genotype and tamoxifen outcomes, does not explicitly mention c.506-1G>A, and is not a case-control prevalence study for this variant.
gnomAD v2.1 reports AF 0.138417 (29,026/209,700 alleles); gnomAD v4.1 reports AF 0.162962 (257,187/1,578,198 alleles). These are population frequencies without an affected-case comparator and do not establish PS4.
PM2ACMGNot met: gnomAD v4.1 grpmax FAF is 0.18481171, far above the <=0.0001 PM2 threshold, with similar non-cancer frequencies.
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Reasoning
PM2 is not met because the variant is common in population controls. No governing VCEP specifies a non-cancer or exome-only source, so the default all-comers data apply; the gnomAD v4.1 filtering grpmax FAF is 0.18481171, far above the generic PM2 supporting threshold of 0.0001. The non-cancer datasets independently show the same conclusion: gnomAD v2.1 non-cancer exomes AF=0.137409 and gnomAD v3.1 non-cancer genomes AF=0.140401.
Rule
Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes or Exome Aggregation Consortium. ... PM2 (supporting): <= 0.0001 — SVI recommendation to downgrade PM2 to Supporting (ClinGen SVI 2020) (PMID:25741868)
Evidence considered
gnomAD v4.1 all-comers filtering grpmax FAF=0.18481171 and total AF=0.16296244197496132.
PP3ACMGNot met: SpliceAI maximum delta 0.005 is below the PP3 supporting threshold of >=0.2 for this canonical splice-site variant.
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Reasoning
The variant is a canonical splice-site/intronic variant, so the applicable generic PP3 path is SpliceAI only; REVEL is not applicable and the BayesDel score is not usable because no generic ACMG-strength calibration is established. SpliceAI maximum delta is 0.005, below the supplied PP3 supporting threshold of >= 0.2 and therefore below the moderate threshold of >= 0.5. The available splice prediction does not support PP3.
Rule
Multiple lines of computational evidence support a deleterious effect on the gene or gene product (conservation, evolutionary, splicing impact, etc.) ... Intronic, synonymous, or splice-region variant -> SpliceAI only. There is no REVEL score to fall back to. ... PP3 (supporting): >= 0.2 — SpliceAI recommended cutoff (Jaganathan et al. 2019, Cell) (PMID:30661751)
Evidence considered
SpliceAI Lookup reports DS_AG 0.001, DS_AL 0.0, DS_DG 0.0, and DS_DL 0.005; maximum delta = 0.005 for NM_000106.6:c.506-1G>A.
For the generic splice-prediction path, the supplied SpliceAI calibration defines PP3 supporting at >= 0.2 and PP3 moderate at >= 0.5 (Jaganathan et al. 2019, Cell, PMID:30661751); the observed maximum delta 0.005 reaches neither threshold.
The local BayesDel score (-0.0238629) was not used because the supplied governing guidance states that no generic ACMG-strength calibration is established for BayesDel.
PP5ACMG_2015Not met: ClinVar has zero expert-panel submissions and no exact-variant expert-panel Pathogenic or Likely pathogenic classification.
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Reasoning
Generic PP5 requires a reputable recent report of the variant as pathogenic when the evidence is unavailable for independent evaluation. The exact-variant ClinVar record has no expert-panel submissions; it contains a laboratory Likely benign submission and other/drug-response submissions, not an exact-variant expert-panel Pathogenic or Likely pathogenic classification. Ordinary laboratory submissions, aggregate labels, and non-expert assertions do not satisfy the required PP5 trigger. Therefore PP5 is not met.
Rule
Reputable source recently reports variant as pathogenic, but the evidence is not available to the laboratory to perform an independent evaluation.
Evidence considered
ClinVar variation 16889 is an exact match for NM_000106.6:c.506-1G>A and reports expert_panels as empty; the record has a GeneDx Likely benign single-laboratory submission and other/drug-response submissions, with no expert-panel pathogenic assertion.
BP6ACMG_2015Not met: the only benign assertion is a single-laboratory Likely benign submission, not an exact-variant ClinVar expert-panel benign or likely benign classification.
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Reasoning
Generic BP6 requires a reputable recent benign report when the evidence is unavailable for independent evaluation. The exact-variant ClinVar record has no expert-panel submissions and its Likely benign assertion is from a single clinical laboratory, while other submissions are drug response or other. Under the specified generic rule, ordinary laboratory submissions, aggregate labels, and non-expert assertions must not trigger BP6. Therefore BP6 is not met.
Rule
Reputable source recently reports variant as benign, but the evidence is not available to the laboratory to perform an independent evaluation.
Evidence considered
ClinVar variation 16889 is an exact match and reports no expert-panel submissions; the benign evidence is a GeneDx single-submitter Likely benign classification, which is excluded from BP6 under the specified rule.
PS2ACMG_2015Not assessed: no documented proband disease, family-history information, or confirmed maternity and paternity testing is available for this variant.
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Reasoning
No case-level proband phenotype, family-history statement, or parental testing result is documented for NM_000106.6:c.506-1G>A. Therefore, de novo status cannot be established, and neither maternity nor paternity confirmation is available to satisfy PS2.
Rule
De novo (both maternity and paternity confirmed) in a patient with the disease and no family history.
Evidence considered
The case evidence contains no proband-level de novo report, parental genotype results, maternity confirmation, paternity confirmation, or family-history assessment for NM_000106.6:c.506-1G>A.
Still missing
Document the proband's relevant disease phenotype and absence or presence of family history.
Obtain and document variant testing in both biological parents with confirmed maternity and paternity.
PM3ACMG_2015Not assessed: no affected-proband observation or parental/offspring phase evidence shows c.506-1G>A in trans with a pathogenic CYP2D6 allele.
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Reasoning
The generic PM3 definition is applicable because CYP2D6 deficient drug-metabolism phenotypes are described as autosomal recessive. However, the available case evidence does not document an affected proband with NM_000106.6:c.506-1G>A, a pathogenic second allele, or parental/offspring testing establishing that the alleles are in trans. Therefore, PM3 cannot be assessed.
Rule
For recessive disorders, detected in trans with a pathogenic variant
Evidence considered
The case evidence identifies CYP2D6 deficient drug-metabolism phenotypes as an autosomal recessive trait, but reports no affected-proband allelic observation for this variant.
No pathogenic second CYP2D6 allele or parental/offspring phase result placing the two alleles in trans is documented in the available evidence.
Still missing
Affected-proband observation linked to NM_000106.6:c.506-1G>A
A specified pathogenic CYP2D6 allele in the same proband
Parental or offspring testing establishing trans phase
PM6ACMG_2015Not assessed: no documented de novo occurrence is reported, so assumed de novo status without parental confirmation cannot be evaluated.
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Reasoning
No case-level report establishes that NM_000106.6:c.506-1G>A arose de novo, and no proband phenotype or parental testing information is provided. The available literature concerns CYP2D6 pharmacogenetic or functional observations rather than an unconfirmed de novo occurrence of this variant.
Rule
Assumed de novo, but without confirmation of paternity and maternity.
Evidence considered
No case-level de novo observation or parental testing result for NM_000106.6:c.506-1G>A is present in the available evidence.
The extracted publications reviewed for this group do not report de novo status, parent-child testing, or segregation for this variant.
Still missing
Provide a case report or clinical record documenting the variant in a proband with the relevant disease phenotype.
Document whether parental testing was unavailable or unperformed and the basis for assuming de novo origin.
PP1ACMG_2015Not assessed: no affected relatives, informative meioses, or family genotype-phenotype segregation data are documented for this variant.
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Reasoning
No affected family members, informative meioses, genotype results in relatives, or phenotype concordance across a family are documented for NM_000106.6:c.506-1G>A. Consequently, co-segregation cannot be assessed or assigned.
Rule
Co-segregation with disease in multiple affected family members in a gene definitively known to cause the disease.
Evidence considered
The available case evidence contains no pedigree, affected-relative testing, segregation analysis, or family-level phenotype data for NM_000106.6:c.506-1G>A.
Still missing
Provide a pedigree identifying affected relatives and their clinical phenotypes.
Provide variant genotypes and phenotype status for informative relatives and the number of informative meioses.
PP4ACMG_2015Not assessed: no patient phenotype or family-history description is available to test the required highly specific disease association.
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Reasoning
The generic PP4 rule requires a patient's phenotype or family history highly specific for a disease with a single genetic etiology. The case evidence supplied for this group provides no patient phenotype, disease diagnosis, or family-history description for this variant; the available literature concerns drug-metabolism or tamoxifen pharmacogenetics rather than a highly specific single-etiology disease phenotype. PP4 cannot be assessed without phenotype or family-history data.
Rule
Patient’s phenotype or family history is highly specific for a disease with a single genetic etiology.
Evidence considered
No patient phenotype, disease diagnosis, or family-history evidence is available in the supplied case evidence for PP4.
Still missing
Patient phenotype, confirmed diagnosis, and relevant family history are not provided.
BS1ACMGNot assessed: frequency is 0.18481171, but disease prevalence, penetrance, allelic heterogeneity, and a maximum-credible-frequency model are unavailable.
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Reasoning
The allele frequency is high, but BS1 requires that it be greater than expected for the specific disorder rather than merely above the generic 1% default. This CYP2D6 variant is a common pharmacogenetic loss-of-function allele, and the available evidence does not establish a disease prevalence, penetrance, allelic heterogeneity model, or maximum credible allele-frequency calculation for a specific disorder. Therefore BS1 is not assessed from the default alone.
Rule
Allele frequency is greater than expected for the disorder. ... BS1 (strong): >= 0.01 — Generic SVI default; per-gene derivation preferred (Whiffin et al. 2017) (PMID:28518168)
Evidence considered
gnomAD v4.1 all-comers filtering grpmax FAF=0.18481171; this is the required filtering allele-frequency metric rather than the Amish popmax point estimate.
Generic BS1 default supplied for this case: >=0.01, with per-gene maximum-credible-frequency analysis preferred under Whiffin et al. 2017 (PMID:28518168).
No VCEP-specific disease prevalence, penetrance, allelic-heterogeneity, or per-gene BS1 threshold is available for CYP2D6 in this case.
Still missing
A disorder-specific maximum credible allele-frequency calculation with prevalence, penetrance, and allelic-heterogeneity inputs is unavailable.
BS2ACMG_2015Not assessed: gnomAD reports 9043 homozygotes, but aggregate counts do not establish healthy adult status or full early-age penetrance.
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Reasoning
The population databases report many homozygotes, including 9043 in gnomAD v4.1, but they do not document that a named individual carrying the variant was a healthy adult, nor do they establish that full penetrance at an early age is expected for a defined CYP2D6 disorder. Aggregate homozygote counts therefore cannot satisfy BS2.
Rule
Observed in a healthy adult individual for a recessive (homozygous), dominant (heterozygous), or X-linked (hemizygous) disorder, with full penetrance expected at an early age.
Evidence considered
gnomAD v4.1 reports 9043 homozygotes among 1578198 observed alleles, but provides no individual-level phenotype or healthy-adult ascertainment for those homozygotes.
Still missing
An individual-level healthy-adult observation tied to a defined, fully penetrant early-onset CYP2D6 disorder is unavailable.
BS3ACMG_2015Not assessed: no variant-specific assay shows absence of damage to CYP2D6 function or splicing; available evidence instead reports aberrant splicing.
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Reasoning
No variant-specific functional study in the reviewed evidence demonstrates that NM_000106.6:c.506-1G>A has no damaging effect on CYP2D6 protein function or splicing. The available functional evidence instead supports abnormal splicing, so it cannot support BS3.
Rule
Well-established in vitro or in vivo functional studies show no damaging effect on protein function or splicing.
Evidence considered
PMID:1978565 was reviewed because it is the available exact-variant functional source; its reported result is abnormal splice recognition, not a benign functional result, so it does not support BS3.
Still missing
A well-established variant-specific functional study demonstrating no damaging effect on CYP2D6 function or splicing is absent.
BS4ACMG_2015Not assessed: no affected relatives with documented variant status are available to demonstrate lack of segregation or exclude phenocopies.
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Reasoning
No affected family members carrying or lacking NM_000106.6:c.506-1G>A are described, so there is no documented non-segregation to evaluate. The absence of family data cannot establish BS4 or permit assessment of phenocopies or additional pathogenic variants in the family.
Rule
Lack of segregation in affected members of a family.
Evidence considered
No affected-relative genotype and phenotype comparisons are documented for NM_000106.6:c.506-1G>A.
Still missing
Provide affected-relative phenotypes and variant test results.
Assess possible phenocopies and the possibility of more than one pathogenic variant if non-segregation is observed.
BP2ACMG_2015Not assessed: no documented cis or trans observation places c.506-1G>A with a pathogenic variant in an affected or tested individual.
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Reasoning
The generic BP2 definition permits assessment for a fully penetrant dominant disorder when the variant is in trans with a pathogenic variant, or for any inheritance pattern when it is in cis with a pathogenic variant. The available case evidence documents neither a trans nor a cis observation involving NM_000106.6:c.506-1G>A and a pathogenic variant. Therefore, BP2 cannot be assessed.
Rule
Observed in trans with a pathogenic variant for a fully penetrant dominant gene/disorder or observed in cis with a pathogenic variant in any inheritance pattern.
Evidence considered
No cis or trans observation involving NM_000106.6:c.506-1G>A and a pathogenic variant is documented in the available case evidence.
No family-genetic or molecular-phasing result establishes the allelic relationship required for BP2.
Still missing
A documented cis or trans observation with a specified pathogenic variant
Phasing or family-genetic data establishing the allelic relationship
BP5ACMG_2015Not assessed: no disease case and no alternate molecular diagnosis are documented for the individual carrying this variant.
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Reasoning
Generic BP5 requires the variant to be found in a case with an alternate molecular basis for disease. The supplied evidence does not provide a disease case description or an alternate molecular diagnosis for the individual carrying NM_000106.6:c.506-1G>A. Drug-response and population records do not establish an alternate molecular basis for disease, so BP5 cannot be assessed.
Rule
Variant found in a case with an alternate molecular basis for disease.
Evidence considered
The available evidence documents pharmacogenetic/drug-response records and population frequency, but no disease case with a separate molecular cause.
Still missing
A documented disease case with an independent alternate molecular basis is not provided.
Not applicable · 8· recorded as not applicableShow reasons ▾Hide reasons ▴PS1N/ANot applicable: PS1 requires a missense variant, and this is a canonical splice-site variant.
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Reasoning
PS1 (Richards et al. 2015, PMID:25741868) requires the same amino acid change as a previously established pathogenic variant, evaluated regardless of the underlying nucleotide change. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, no altered amino acid exists at this position to compare against any previously established pathogenic missense variant, so PS1's structural prerequisite is not met by this variant class. No VCEP criteria specification covers PS1 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_missense
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PM1N/ANot applicable: PM1 requires a missense variant, and this is a canonical splice-site variant.
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Reasoning
PM1 (Richards et al. 2015, PMID:25741868) applies to a missense variant located in a mutational hot spot and/or a critical, well-established functional domain without benign variation. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, no altered residue exists to evaluate for mutational hot-spot or critical-domain membership, so PM1's structural prerequisite is not met by this variant class. No VCEP criteria specification covers PM1 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_missense
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PM4N/ANot applicable: PM4 requires a protein-length change, and this is a canonical splice-site variant.
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Reasoning
PM4 (Richards et al. 2015, PMID:25741868) applies to protein length changes: in-frame insertions/deletions in a non-repetitive region, or stop-loss variants that extend the protein past the reference stop codon. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, no change in protein length occurs, so there is nothing for this criterion to evaluate, so PM4's structural prerequisite is not met by this variant class. No VCEP criteria specification covers PM4 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
PM5N/ANot applicable: PM5 requires a missense variant, and this is a canonical splice-site variant.
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Reasoning
PM5 (Richards et al. 2015, PMID:25741868) requires a novel missense change at an amino acid residue where a different missense change has previously been determined to be pathogenic. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, no missense change exists at this residue to compare against a different pathogenic missense change at the same position, so PM5's structural prerequisite is not met by this variant class. No VCEP criteria specification covers PM5 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_missense
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PP2N/ANot applicable: PP2 requires a missense variant, and this is a canonical splice-site variant.
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Reasoning
PP2 (Richards et al. 2015, PMID:25741868) applies to a missense variant in a gene with a low rate of benign missense variation, where missense variants are a common mechanism of disease. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, the gene's missense-constraint properties are irrelevant because no missense change is present to evaluate, so PP2's structural prerequisite is not met by this variant class. No VCEP criteria specification covers PP2 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_missense
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
BP1N/ANot applicable: BP1 requires a missense variant, and this is a canonical splice-site variant.
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Reasoning
BP1 (Richards et al. 2015, PMID:25741868) applies to a missense variant in a gene for which primarily truncating variants are known to cause disease. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, the gene's truncating-variant mechanism is irrelevant because no missense change is present to evaluate, so BP1's structural prerequisite is not met by this variant class. No VCEP criteria specification covers BP1 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_missense
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
BP3N/ANot applicable: BP3 requires an in-frame indel in a repeat region, and this is a canonical splice-site variant.
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Reasoning
BP3 (Richards et al. 2015, PMID:25741868) applies to in-frame insertions/deletions located in a repetitive region without a known function. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, the variant does not alter protein length within a repeat region, so there is nothing for this criterion to evaluate, so BP3's structural prerequisite is not met by this variant class. No VCEP criteria specification covers BP3 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
BP7N/ANot applicable: BP7 requires a synonymous variant, and this is a canonical splice-site variant.
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Reasoning
BP7 (Richards et al. 2015, PMID:25741868) is defined for a synonymous (silent) variant for which splicing prediction algorithms predict no impact to the splice consensus sequence and the nucleotide is not highly conserved. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, the encoded protein sequence is altered, so the criterion's silent-variant premise does not hold regardless of any splicing prediction, so BP7's structural prerequisite is not met by this variant class. No VCEP criteria specification covers BP7 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_synonymous
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
Identifiers
Gene
CYP2D6
Transcript
NM_000106.6
Coding (HGVS c.)
NM_000106.6:c.506-1G>A
Protein (HGVS p.)
NP_000097.3:p.?
GRCh38
chr22:42128945 C>T
GRCh37
chr22:42524947 C>T
Location and type
Intron 3 · canonical splice
ClinVar
16889
COSMIC
COSV62243440
Gene diagram
Every interpreted variant in CYP2D6, mapped onto the exon structure of NM_000106.6. Select a row to find it on the plot.
CYP2D6NM_000106.6
Fetching transcript structure from UCSC…
Exons
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Transcript span
—
Strand
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Variants mapped
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Source
UCSC ncbiRefSeqCurated
All variants in CYP2D6—Select a row to find it on the plot; use the link to open its page.
AF 0.16 · 257187 / 1,578,198 alleles · 9043 hom · FAF 0.18
Amish214 / 898
0.2429 hom
European (non-Finnish)215160 / 1,160,082
0.197090 hom
Ashkenazi Jewish5115 / 28,966
0.18296 hom
Remaining individuals9057 / 61,150
0.15410 hom
Admixed American6405 / 54,812
0.12292 hom
European (Finnish)6289 / 62,010
0.1240 hom
South Asian8810 / 87,366
0.1367 hom
Middle Eastern589 / 5,978
0.09919 hom
African/African American5415 / 73,310
0.074295 hom
East Asian133 / 43,626
0.0035 hom
gnomAD v2.1
AF 0.14 · 29026 / 209,700 alleles · 2670 hom · FAF 0.19
European (non-Finnish)17283 / 88,202
0.21825 hom
Ashkenazi Jewish1649 / 9,086
0.18160 hom
Remaining individuals911 / 5,902
0.1586 hom
Admixed American3035 / 27,340
0.11197 hom
South Asian2540 / 24,506
0.1172 hom
European (Finnish)2095 / 20,914
0.1110 hom
African/African American1464 / 18,270
0.08120 hom
East Asian49 / 15,480
0.0032
Statements
gnomAD v4.1
This variant is present in gnomAD v4.1 (AF= 0.162962; MAF= 16.29624%, 257187/1578198 alleles, homozygotes = 9043) and has highest observed frequency in the Amish population (AF= 0.238307; MAF= 23.83073%, 214/898 alleles, homozygotes = 29); grpmax FAF= 0.184812.
gnomAD v2.1
This variant is present in gnomAD v2.1 (AF= 0.138417; MAF= 13.84168%, 29026/209700 alleles, homozygotes = 2670) and has highest observed frequency in the European (non-Finnish) population (AF= 0.195948; MAF= 19.59479%, 17283/88202 alleles, homozygotes = 1825); grpmax FAF= 0.194193.
gnomAD-Canada
Not available in gnomAD-Canada v1.0.
SpliceAI and Pangolin
SpliceAI acceptor lossat -131 bp
0.000
SpliceAI acceptor gainat -301 bp
0.001
SpliceAI donor lossat -65 bp
0.005
SpliceAI donor gainat -389 bp
0.000
Pangolin splice lossmagnitude shown
-0.007
Pangolin splice gain
0.009
Other predictors
REVEL
Not available
BayesDel
-0.024
How the predictions were used
BP4SupportingACMGMet at supporting strength: SpliceAI maximum delta 0.005 is below the BP4 cutoff of <=0.1 for this canonical splice-site variant.
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Reasoning
The variant is a canonical splice-site/intronic variant, so the applicable generic BP4 path is SpliceAI only; REVEL is not applicable. SpliceAI maximum delta is 0.005, which is at or below the supplied BP4 supporting cutoff of <= 0.1, supporting no predicted splice impact at supporting strength. This computational result is not combined with the BayesDel score, which has no established generic ACMG-strength calibration.
Rule
Multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc) ... Intronic, synonymous, or splice-region variant -> SpliceAI only. There is no REVEL score to fall back to. ... BP4 (supporting): <= 0.1 — SpliceAI recommended cutoff (Jaganathan et al. 2019, Cell) (PMID:30661751)
Evidence considered
SpliceAI Lookup reports DS_AG 0.001, DS_AL 0.0, DS_DG 0.0, and DS_DL 0.005; maximum delta = 0.005 for NM_000106.6:c.506-1G>A.
For the generic splice-prediction path, the supplied SpliceAI calibration defines BP4 supporting at <= 0.1 (Jaganathan et al. 2019, Cell, PMID:30661751); the observed maximum delta 0.005 meets this threshold.
The local BayesDel score (-0.0238629) was not used because the supplied governing guidance states that no generic ACMG-strength calibration is established for BayesDel.
PP3ACMGNot met: SpliceAI maximum delta 0.005 is below the PP3 supporting threshold of >=0.2 for this canonical splice-site variant.
Details ▾Hide ▴
Reasoning
The variant is a canonical splice-site/intronic variant, so the applicable generic PP3 path is SpliceAI only; REVEL is not applicable and the BayesDel score is not usable because no generic ACMG-strength calibration is established. SpliceAI maximum delta is 0.005, below the supplied PP3 supporting threshold of >= 0.2 and therefore below the moderate threshold of >= 0.5. The available splice prediction does not support PP3.
Rule
Multiple lines of computational evidence support a deleterious effect on the gene or gene product (conservation, evolutionary, splicing impact, etc.) ... Intronic, synonymous, or splice-region variant -> SpliceAI only. There is no REVEL score to fall back to. ... PP3 (supporting): >= 0.2 — SpliceAI recommended cutoff (Jaganathan et al. 2019, Cell) (PMID:30661751)
Evidence considered
SpliceAI Lookup reports DS_AG 0.001, DS_AL 0.0, DS_DG 0.0, and DS_DL 0.005; maximum delta = 0.005 for NM_000106.6:c.506-1G>A.
For the generic splice-prediction path, the supplied SpliceAI calibration defines PP3 supporting at >= 0.2 and PP3 moderate at >= 0.5 (Jaganathan et al. 2019, Cell, PMID:30661751); the observed maximum delta 0.005 reaches neither threshold.
The local BayesDel score (-0.0238629) was not used because the supplied governing guidance states that no generic ACMG-strength calibration is established for BayesDel.
BP7N/ANot applicable: BP7 requires a synonymous variant, and this is a canonical splice-site variant.
Details ▾Hide ▴
Reasoning
BP7 (Richards et al. 2015, PMID:25741868) is defined for a synonymous (silent) variant for which splicing prediction algorithms predict no impact to the splice consensus sequence and the nucleotide is not highly conserved. NM_000106.6:c.506-1G>A in CYP2D6 is a variant at a canonical ±1/2 splice-consensus position predicted to produce NP_000097.3:p.?. As a result, the encoded protein sequence is altered, so the criterion's silent-variant premise does not hold regardless of any splicing prediction, so BP7's structural prerequisite is not met by this variant class. No VCEP criteria specification covers BP7 for CYP2D6, so the generic ACMG/AMP 2015 definition applies. This determination was made deterministically from the variant's consequence class, prior to LLM adjudication.
Rule
deterministic_prefilter: requires_synonymous
Evidence considered
Deterministic consequence classification: canonical_splice (prefetch.json normalized protein consequence)
VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
Statement
In silico
SpliceAI predicts no significant splice impact for this variant (max delta score = 0.01). BayesDel score = -0.0238629.
10 paper records listed. 1 cited in the classification.
Cited in the classification
The human CYP2D locus associated with a common genetic defect in drug oxidation: a G1934----A base change in intron 3 of a mutant CYP2D6 allele results in an aberrant 3' splice recognition site.
Hanioka N et al. · 1990 Dec
The paper identifies the CYP2D6 intron 3 G-to-A splice-site change corresponding to NM_000106.6:c.506-1G>A as a cause of aberrant 3' splice recognition; the case evidence further records a single-base deletion, frameshift, and predicted truncated protein consequence.
The human CYP2D locus associated with a common genetic defect in drug oxidation: a G1934----A base change in intron 3 of a mutant CYP2D6 allele results in an aberrant 3' splice recognition site.
Location Article title
Context Variant-specific molecular study of a CYP2D6 allele from an individual with deficient debrisoquine metabolism, including sequence analysis and assessment of aberrant splice recognition.
Other recorded publications
Identification of the primary gene defect at the cytochrome P450 CYP2D locus.
Multiple mutations of the human cytochrome P450IID6 gene (CYP2D6) in poor metabolizers of debrisoquine. Study of the functional significance of individual mutations by expression of chimeric genes.
CYP2D6 genotype and adjuvant tamoxifen: meta-analysis of heterogeneous study populations.
Province MA et al. · 2014
The paper evaluates CYP2D6 genotype and tamoxifen outcomes in 4,973 treated patients but does not explicitly mention c.506-1G>A and provides no variant-specific PS4 case-control result.
CYP2D6-mediated metabolism is the rate-limiting enzymatic step for the formation of endoxifen, the most abundant active metabolite.
Introduction, paragraph 1
Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer.
This pharmacokinetic study reports CYP2D6 activity-score associations in 587 tamoxifen-treated patients but does not mention c.506-1G>A or provide variant-specific case-control evidence.
There was a strong gene-dose effect for an association between the CYP2D6 activity score and endoxifen concentrations (P<10−40) in all ethnic cohorts (Figure 3a).
Results, “Tamoxifen metabolite profiling, compliance and CYP2D6 activity”
Tamoxifen and CYP2D6: A Controversy in Pharmacogenetics.
This review discusses CYP2D6 polymorphism and tamoxifen metabolism generally but does not mention c.506-1G>A or provide variant-specific phenotype, case-control, or population evidence.
The CYP2D6 gene is highly polmorphic. CYP2D6 has over 100 distinct variants, and frequent gene duplications and deletions.
Section 2, “CYP2D6 and Tamoxifen Metabolism,” page 69
Pan-cancer repository of validated natural and cryptic mRNA splicing mutations.
This genome-wide cancer-splicing resource describes population-scale splice analysis but does not provide a CYP2D6 c.506-1G>A-specific result or case-control phenotype evidence.
The evidence statements recorded by the interpretation pipeline. They have not been reinterpreted by the page.
gnomAD v4.1
This variant is present in gnomAD v4.1 (AF= 0.162962; MAF= 16.29624%, 257187/1578198 alleles, homozygotes = 9043) and has highest observed frequency in the Amish population (AF= 0.238307; MAF= 23.83073%, 214/898 alleles, homozygotes = 29); grpmax FAF= 0.184812.
gnomAD v2.1
This variant is present in gnomAD v2.1 (AF= 0.138417; MAF= 13.84168%, 29026/209700 alleles, homozygotes = 2670) and has highest observed frequency in the European (non-Finnish) population (AF= 0.195948; MAF= 19.59479%, 17283/88202 alleles, homozygotes = 1825); grpmax FAF= 0.194193.
gnomAD-Canada
Not available in gnomAD-Canada v1.0.
ClinVar
This variant has been reported in ClinVar as other (1 clinical laboratory) and as Likely benign (1 clinical laboratory). (ClinVarID = 16889)
In silico
SpliceAI predicts no significant splice impact for this variant (max delta score = 0.01). BayesDel score = -0.0238629.
Somatic
This variant has previously been reported in somatic cancers (COSMIC; COSV62243440, n = 12 times).