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Variant interpretation report

CFTR c.3846G>A, p.Trp1282Ter

NM_000492.4:c.3846G>A NP_000483.3:p.(Trp1282Ter) Nonsense · exon 23 View identifiers
Classification
Pathogenic

Variant description:

The CFTR NM_000492.4:c.3846G>A (NP_000483.3:p.(Trp1282Ter)) nonsense variant has previously been reported in somatic cancers (COSMIC; COSV99069637, n = 1 time). This variant is predicted to result in an absent or disrupted protein product. Experimental evidence: W1282X abolished chloride transport, while correction restored CFTR protein to approximately 10% of wild-type levels and restored channel activity. Based on available guidelines, this variant is considered to be Pathogenic. This variant is considered to be Pathogenic by the VCEP (CFTR2; ClinVar ID 7129).

Five-step scale from benign to pathogenic. This variant is pathogenic. Select a step to read what it means.

Pathogenic.A pathogenic classification under the recorded framework.

In plain language

Gene-level background from the recorded interpretation.

About CFTR

CFTR encodes an ATP-binding cassette family protein that functions as a chloride channel, helping regulate salt and water movement across epithelial tissues. Disruption of CFTR causes cystic fibrosis, an inherited disorder affecting the lungs, digestive system, and other organs; CFTR has no established primary role in cancer.

LYFE Sciences is an AI system, and it can make mistakes. Criteria may be applied incorrectly, sources may be misread, and a confident-looking classification can still be wrong. Double-check every criterion and its underlying evidence before relying on any call.
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.

Pathogenic evidence criteria: 5 Benign evidence criteria: 0
Pathogenic criteria applied · 5
PVS1Very strong
PVS1 · very strong

Met at very strong strength: CFTR c.3846G>A is a nonsense variant producing W1282X, with minimal functional protein and abolished chloride transport.

PS3Supporting
PS3 · supporting

Met, supporting: W1282X abolished chloride transport, while correction restored CFTR protein to approximately 10% of wild-type levels and restored channel activity.

PS4Strong
PS4 · strong

Met: W1282X shows a computed case-control OR of 199.6 (95% CI 159.7-249.4), exceeding the >5.0 threshold with a confidence interval excluding 1.0.

PM2Supporting
PM2 · supporting

Met at supporting: gnomAD v4.1 grpmax FAF is 6.312e-05, below the generic PM2 supporting threshold of 0.0001.

PP5Supporting
PP5 · supporting

Met: ClinVar reports the exact c.3846G>A (p.Trp1282Ter) variant as Pathogenic by the CFTR2 expert panel, satisfying the instructed PP5 rule.

Benign criteria applied · 0

No benign criterion marked as applied in the recorded assessment.

Recorded classification: Pathogenic

Pathogenic: PVS1 (very strong) plus PS4 (strong) satisfy the generic ACMG/AMP 2015 Pathogenic rule, with PS3, PM2, and PP5 supporting.

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
421 / 1,613,376 alleles

gnomAD v4.1: 421 / 1,613,376 alleles. Recorded AF 0.000260944. Recorded homozygote count 1.

gnomAD v2.1

This variant is present in gnomAD v2.1 (AF= 0.000428649; MAF= 0.04286%, 121/282282 alleles, homozygotes = 0) and has highest observed frequency in the Ashkenazi Jewish population (AF= 0.00965251; MAF= 0.96525%, 100/10360 alleles, homozygotes = 0); grpmax FAF= 8.828e-05.

gnomAD-Canada

Not available in gnomAD-Canada v1.0.

SpliceAI score
0.014 maximum delta

Recorded SpliceAI maximum delta score: 0.014. Refer to the recorded PP3/BP4 rationale for interpretation.

No listed criterion applied SpliceAI ↗
ClinVar submissions
32 reported laboratory submissions

30 Pathogenic · 2 pathogenic. ClinVar API review status: practice guideline.

No screenshot for this evidence
Functional evidence
Not recorded

No standalone functional evidence summary is recorded in evidence_summary.functional.

COSMIC
Cancer Hotspots
Somatic evidence
1 recorded samples

This variant has previously been reported in somatic cancers (COSMIC; COSV99069637, n = 1 times).

Cancer Hotspots

This variant does not lie in a statistically significant hotspot.

For specialists

Technical detail

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: 5 met · 3 not met · 10 not assessed · 10 not applicable. Open any row for the full reasoning, the rule and the evidence behind it.

Met Not met Not assessed Not applicable

PS4 is met from a directly verified affected-case frequency report and a computed matched-ancestry case-control comparison.

PP4 and BP5 remain not assessed because the patient phenotype/family history and alternate molecular basis are not provided.

PP5 is met only from the exact-variant ClinVar CFTR2 expert-panel Pathogenic classification; BP6 is not assessed because no benign expert-panel assertion is available.

Met · 5

PVS1 Very strongACMG_2015Met at very strong strength: CFTR c.3846G>A is a nonsense variant producing W1282X, with minimal functional protein and abolished chloride transport. Details ▾Hide ▴
Reasoning

PVS1 is met at full strength. NM_000492.4:c.3846G>A is a nonsense variant in the relevant CFTR transcript, producing NP_000483.3:p.(Trp1282Ter) (W1282X) in exon 23. CFTR loss of function is an established disease mechanism in the supplied gene-level assessment. Variant-specific evidence describes W1282X as producing minimal functional CFTR protein and abolishing chloride transport, while CFTR premature-termination variants are associated with severe RNA reduction and little or no protein production. No named downgrade rule is triggered: this is not a terminal-exon or non-critical-distal-region exception, and there is no evidence that the predicted truncation escapes the relevant loss-of-function mechanism. Therefore the generic ACMG/AMP PVS1 definition is satisfied without downgrade.

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
  • Variant assessment: NM_000492.4:c.3846G>A is a nonsense change producing NP_000483.3:p.(Trp1282Ter), also known as W1282X, in exon 23.
  • Gene-level PVS1 assessment: CFTR loss of function is supported as a germline disease mechanism, making generic PVS1 assessment eligible.
  • CFTR2 analysis summarized in the extracted paper evidence reports that premature-termination variants commonly cause nonsense-mediated decay with severe reduction of CFTR RNA and little or no protein production.
  • W1282X is explicitly described in a bronchial epithelial cell model as an exon 23 G>A nonsense mutation producing minimal functional CFTR protein and abolishing chloride transport.
  • The variant is reported as W1282X in CF patient mutation-frequency data, corresponding to NM_000492.4:c.3846G>A and NP_000483.3:p.(W1282*).
Sources
PS3 SupportingACMG_2015Met, supporting: W1282X abolished chloride transport, while correction restored CFTR protein to approximately 10% of wild-type levels and restored channel activity. Details ▾Hide ▴
Reasoning

PS3 is met at supporting strength. PMID:32332735 directly studied CFTR W1282X, corresponding to NM_000492.4:c.3846G>A and p.(W1282*), in homozygous human bronchial epithelial cells. The paper reports that W1282X produces minimal functional CFTR protein and abolishes chloride transport; adenine-base correction restored full-length CFTR protein to approximately 10% of wild-type levels and restored CFTR chloride-channel activity in corrected clones. This provides variant-specific, biologically relevant evidence of loss of CFTR function with a rescue control. The evidence is from a research cell model rather than validated, reproducible, and robust clinical diagnostic laboratory testing, so it does not justify stronger-than-supporting calibration under the generic rule.

Rule
Well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product. Note: Functional studies that have been validated and shown to be reproducible and robust in a clinical diagnostic laboratory setting are considered the most well-established.
Evidence considered
  • Chemical modifications of adenine base editor mRNA and guide RNA expand its application scope (PMID:32332735), Results: homozygous CFTR W1282X bronchial epithelial cells were studied; W1282X was reported to produce minimal functional CFTR protein and abolish chloride transport.
  • PMID:32332735, Results and Fig. 2: modified adenine-base editing achieved a 26.4 ± 7.40% target-site conversion rate, restored full-length CFTR protein to approximately 10% of wild-type cells, and restored CFTR chloride-channel activity in corrected clones.
Still missing
  • The functional evidence comes from one research cell-model study and is not documented as validated, reproducible, and robust clinical diagnostic laboratory testing.
Sources
PS4 StrongACMG_2015Met: W1282X shows a computed case-control OR of 199.6 (95% CI 159.7-249.4), exceeding the >5.0 threshold with a confidence interval excluding 1.0. Details ▾Hide ▴
Reasoning

PS4 is met. Watson et al. (PMID:15371902) reported W1282X, corresponding to NM_000492.4:c.3846G>A / p.(W1282*), in 1.50% of 37,263 non-Hispanic Caucasian CF patient chromosomes. Using the matched-ancestry gnomAD v4.1 NFE control frequency of 90/1,179,672 alleles, the published rounded case frequency corresponds to approximately 559 case alleles; I computed the allele-frequency case-control OR as 199.6 with an approximate 95% CI of 159.7-249.4. The OR is >5.0 and the CI excludes 1.0. The paper did not print an OR, so this comparison was calculated from the reported case and control counts/frequencies.

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
  • Watson et al. 2004, Table 1 and Data sources: W1282X frequency was 1.50% among non-Hispanic Caucasian individuals with clinically diagnosed cystic fibrosis; the case dataset included 37,263 non-Hispanic Caucasian CF chromosomes.
  • gnomAD v4.1 NFE: 90/1,179,672 alleles (AF 0.0000762924) used as the matched-ancestry control frequency.
  • Computed from the reported values: approximately 559/37,263 case alleles versus 90/1,179,672 control alleles; OR 199.6, approximate 95% CI 159.7-249.4.
Sources
PM2 SupportingACMGMet at supporting: gnomAD v4.1 grpmax FAF is 6.312e-05, below the generic PM2 supporting threshold of 0.0001. Details ▾Hide ▴
Reasoning

PM2 supporting is met. No VCEP-specific source restriction governs this generic interpretation, so the all-comers gnomAD datasets are the default. The relevant grpmax FAF is 8.828e-05 in gnomAD v2.1 and 6.312e-05 in gnomAD v4.1, both at or below the generic PM2 supporting threshold of <=0.0001. The variant is observed at low frequency rather than absent, so it is not eligible for a stronger absence-based interpretation.

Rule
PM2 (supporting): <= 0.0001 — SVI recommendation to downgrade PM2 to Supporting (ClinGen SVI 2020)
Evidence considered
  • gnomAD v2.1 all-comers reports grpmax FAF = 8.828e-05, with 121/282282 total observed alleles and 0 homozygotes.
  • gnomAD v4.1 all-comers reports grpmax FAF = 6.312e-05, with 421/1613376 total observed alleles and 1 homozygote.
  • Both filtering FAF values are <=0.0001, meeting the supplied generic PM2 supporting threshold; because the variant is present in gnomAD, the conclusion is supporting PM2 rather than complete absence from controls.
Sources
PP5 SupportingACMG_2015Met: ClinVar reports the exact c.3846G>A (p.Trp1282Ter) variant as Pathogenic by the CFTR2 expert panel, satisfying the instructed PP5 rule. Details ▾Hide ▴
Reasoning

Expert panel CFTR2 classified as Pathogenic.

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 record 7129, source_data.variant_title: NM_000492.4(CFTR):c.3846G>A (p.Trp1282Ter); source_data.expert_panels.Pathogenic: CFTR2.
  • ClinVar evidence sentence: the variant is reported as Pathogenic by CFTR2 (expert panel); ordinary laboratory submissions were not used to trigger PP5.
  • ClinVar expert panel classification
Sources

Not met · 3 · evaluated, threshold not reached

BA1 ACMGNot met: gnomAD grpmax FAF is 6.312e-05, far below the generic BA1 threshold of 0.05 despite a 0.943% Ashkenazi Jewish popmax point estimate. Details ▾Hide ▴
Reasoning

BA1 is not met. Under the generic default, BA1 requires allele frequency >=0.05. The relevant filtering metric is gnomAD grpmax FAF, not the Ashkenazi Jewish popmax point estimate: grpmax FAF is 8.828e-05 in gnomAD v2.1 and 6.312e-05 in gnomAD v4.1, both far below 0.05. Although the Ashkenazi Jewish point estimates are approximately 0.965% and 0.943%, respectively, the variant is a well-documented CFTR W1282X pathogenic allele with an expert-panel pathogenic ClinVar record, so the default 5% rule cannot be used to override the disease association.

Rule
BA1 (stand-alone): >= 0.05 — ACMG/AMP 2015 stand-alone benign allele frequency (PMID:25741868)
Evidence considered
  • gnomAD v2.1 all-comers: 121/282282 alleles, total AF 0.000428649, Ashkenazi Jewish popmax point estimate 100/10360 = 0.00965251, and grpmax FAF = 8.828e-05.
  • gnomAD v4.1 all-comers: 421/1613376 alleles, total AF 0.000260944, Ashkenazi Jewish popmax point estimate 279/29578 = 0.00943269, and grpmax FAF = 6.312e-05.
  • The Ashkenazi Jewish observed allele counts exceed 2000 alleles in both datasets, but the required filtering FAF remains far below 0.05; therefore the popmax point estimates do not establish BA1.
  • ClinVar variation 7129 records CFTR c.3846G>A (p.Trp1282Ter) as Pathogenic with CFTR2 expert-panel review.
  • Cystic fibrosis population carrier screening: 2004 revision of American College of Medical Genetics mutation panel, Table 1: W1282X is reported among clinically diagnosed cystic fibrosis patient chromosomes, including 45.92% of Ashkenazi Jewish CF chromosomes.
Sources
BS1 ACMGNot met: the highest qualifying gnomAD filtering FAF is 8.828e-05, below the generic BS1 threshold of 0.01; Ashkenazi Jewish popmax AF is not the permitted metric. Details ▾Hide ▴
Reasoning

BS1 is not met on the generic frequency threshold. The generic default is grpmax FAF >=0.01, and the appropriate filtering values are 8.828e-05 in gnomAD v2.1 and 6.312e-05 in gnomAD v4.1, both below 0.01. The Ashkenazi Jewish popmax point estimates near 0.95% are not used for BS1 because FAF, rather than popmax AF, is the required small-sample-resistant metric. The disease is cystic fibrosis, a severe early-onset autosomal-recessive disorder, so no reduced-penetrance or late-onset exception is supported by the available evidence.

Rule
BS1 (strong): >= 0.01 — Generic SVI default; per-gene derivation preferred (Whiffin et al. 2017) (PMID:28518168)
Evidence considered
  • gnomAD v2.1 all-comers reports grpmax FAF = 8.828e-05; the Ashkenazi Jewish point estimate is 0.00965251 from 100/10360 alleles.
  • gnomAD v4.1 all-comers reports grpmax FAF = 6.312e-05; the Ashkenazi Jewish point estimate is 0.00943269 from 279/29578 alleles.
  • The qualifying Ashkenazi Jewish population has more than 2000 observed alleles in both datasets, but its filtering FAF is below 0.01, so BS1 is not met.
  • The available disease context identifies CFTR-related cystic fibrosis, an early-onset autosomal-recessive disorder; no evidence supports treating this allele as a reduced-penetrance or late-onset exception to the generic assessment.
Sources
BS3 ACMG_2015Not met: W1282X abolished chloride transport and produced minimal functional CFTR protein, while correction restored protein expression and channel activity. Details ▾Hide ▴
Reasoning

BS3 is not met. The available variant-specific functional study does not show no damaging effect; it reports that CFTR W1282X produces minimal functional protein and abolishes chloride transport in homozygous human bronchial epithelial cells. Correction of the variant restored CFTR protein and chloride-channel activity, which is evidence of damaging loss of function rather than preserved protein function or splicing.

Rule
Well-established in vitro or in vivo functional studies show no damaging effect on protein function or splicing.
Evidence considered
  • PMID:32332735, Results: the W1282X model was reported to produce minimal functional CFTR protein and abolish chloride transport; corrected clones regained CFTR expression and chloride-channel activity, so the study does not support a benign functional effect.
Sources

Not assessed · 10 · no assessment recorded

PS2 ACMG_2015Not assessed: no documented de novo finding with both maternity and paternity confirmed and no family history. Details ▾Hide ▴
Reasoning

The available case evidence does not document that NM_000492.4:c.3846G>A is de novo in the proband, does not provide confirmed maternity and paternity, and does not establish absence of a family history. Therefore the PS2 definition cannot be assessed.

Rule
De novo (both maternity and paternity confirmed) in a patient with the disease and no family history.
Evidence considered
  • The available case materials contain no documented parental testing, maternity confirmation, paternity confirmation, or family-history assessment for this variant.
Still missing
  • Proband-level variant testing result
  • Confirmed maternity and paternity testing
  • Documented family history
PM3 ACMG_2015Not assessed: no parent/offspring phase testing or affected-proband genotype demonstrates c.3846G>A in trans with a pathogenic CFTR variant. Details ▾Hide ▴
Reasoning

PM3 cannot be assessed from the available evidence. The governing recessive-disease path requires the variant to be detected in trans with a pathogenic variant and requires parent or offspring testing to determine phase. The case contains no phase-resolved parent/offspring testing, no affected-proband genotype demonstrating a pathogenic CFTR variant on the other allele, and no documented trans or cis relationship. ClinVar's pathogenic classification for c.3846G>A and aggregate reports of W1282X among CF patient chromosomes do not establish PM3 and are not used as a substitute for phase evidence.

Rule
For recessive disorders, detected in trans with a pathogenic variant ... This requires testing of parents (or offspring) to determine phase.
Evidence considered
  • ClinVar records NM_000492.4:c.3846G>A (p.Trp1282Ter) as Pathogenic by an expert panel, but the record provides no phase-resolved parental or offspring genotype for this case.
  • Li et al. 2004, Table 1, reports W1282X frequencies among CF patient chromosomes but does not report an affected-proband second allele or phase information for this variant.
  • No affected-proband genotype with a pathogenic CFTR allele in trans is documented in the supplied case evidence.
Still missing
  • Parent or offspring testing and a documented pathogenic allele in trans are needed to assess PM3.
Sources
PM6 ACMG_2015Not assessed: no documented assumed de novo occurrence or parental testing information is available. Details ▾Hide ▴
Reasoning

The available case evidence does not document an assumed de novo occurrence of NM_000492.4:c.3846G>A. There is no proband-level de novo observation or parental testing information sufficient to evaluate PM6.

Rule
Assumed de novo, but without confirmation of paternity and maternity.
Evidence considered
  • The available case materials contain no documented de novo assessment or parental genotype results for this variant.
Still missing
  • Proband-level de novo observation
  • Parental testing information
PP1 ACMG_2015Not assessed: no multiple affected relatives, informative meioses, or variant-disease segregation data are documented. Details ▾Hide ▴
Reasoning

The available case evidence does not identify multiple affected family members carrying NM_000492.4:c.3846G>A, provide informative meioses, or document segregation of the variant with disease. PP1 therefore cannot be assessed.

Rule
Co-segregation with disease in multiple affected family members in a gene definitively known to cause the disease.
Evidence considered
  • The available case materials contain no family pedigree, affected-relative testing, or segregation results for this variant.
Still missing
  • Affected relatives and their clinical status
  • Variant testing results in affected relatives
  • Informative meioses or pedigree data
PP4 ACMG_2015Not assessed: the patient's phenotype and family history are not provided, so phenotype specificity for a single genetic etiology cannot be judged. Details ▾Hide ▴
Reasoning

PP4 cannot be assessed because the case materials do not provide the patient's clinical phenotype or family history. Population reports of W1282X in clinically diagnosed cystic fibrosis patients do not establish that this patient's phenotype is highly specific for cystic fibrosis.

Rule
Patient’s phenotype or family history is highly specific for a disease with a single genetic etiology.
Still missing
  • Patient clinical phenotype and family history, including diagnostic findings and competing etiologies, are required to assess PP4.
BS2 ACMG_2015Not assessed: gnomAD v4.1 shows one homozygote, but it provides no evidence that the individual was a healthy adult beyond the expected age of CF penetrance. Details ▾Hide ▴
Reasoning

BS2 is not assessed. gnomAD v4.1 reports one homozygote among 1,613,376 alleles, while gnomAD v2.1 reports no homozygotes; however, the record does not establish that the homozygous individual was a healthy adult, had reached the expected age of penetrance, or was phenotyped for cystic fibrosis. A homozygote count alone 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 v2.1 reports 0 homozygotes for 121 observed alleles.
  • gnomAD v4.1 reports 1 homozygote for 421 observed alleles and 1,613,376 total alleles; the dataset record does not provide the individual's age, health status, or cystic-fibrosis phenotype.
Still missing
  • Healthy-adult status, age, and clinical phenotype of the gnomAD v4.1 homozygous individual are unavailable.
Sources
BS4 ACMG_2015Not assessed: no affected relatives with documented negative testing for NM_000492.4:c.3846G>A are reported. Details ▾Hide ▴
Reasoning

The available case evidence does not document affected family members who were tested negative for NM_000492.4:c.3846G>A. Without identified affected relatives, phenotype assessment, and genotype results, lack of segregation cannot be evaluated.

Rule
Lack of segregation in affected members of a family.
Evidence considered
  • The available case materials contain no documented affected relatives with negative testing for this variant and no family segregation analysis.
Still missing
  • Affected relatives with reliable phenotype assessment
  • Genotype results for affected relatives
  • Family structure and segregation information
BP2 ACMG_2015Not assessed: no documented cis pathogenic variant or phase-resolved trans observation satisfies either BP2 allelic configuration. Details ▾Hide ▴
Reasoning

BP2 cannot be assessed from the available evidence. The rule requires either observation in trans with a pathogenic variant for a fully penetrant dominant gene/disorder or observation in cis with a pathogenic variant in any inheritance pattern. No phase-resolved cis observation with a pathogenic variant is documented, and no phase-resolved trans observation in a fully penetrant dominant disorder is documented. The ClinVar pathogenic classification of the target variant does not establish either BP2 allelic configuration.

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
  • ClinVar records NM_000492.4:c.3846G>A (p.Trp1282Ter) as Pathogenic by an expert panel, but this classification does not document a cis pathogenic variant or a qualifying phase-resolved trans observation.
  • No phase-resolved cis or qualifying dominant-disorder trans observation is documented in the supplied case evidence.
Still missing
  • Phase-resolved testing documenting a pathogenic variant in cis, or a qualifying trans observation for a fully penetrant dominant disorder, is needed to assess BP2.
Sources
BP5 ACMG_2015Not assessed: no evidence shows that this case has an alternate molecular basis for disease in addition to c.3846G>A. Details ▾Hide ▴
Reasoning

BP5 cannot be assessed because the case materials contain no evidence that this variant was found in a case with an alternate molecular basis for disease. The variant's pathogenic ClinVar classification and CFTR literature do not establish an alternate molecular cause in the case.

Rule
Variant found in a case with an alternate molecular basis for disease.
Still missing
  • Case-level molecular findings establishing an alternate disease-causing variant or other alternate molecular basis are required to assess BP5.
BP6 ACMG_2015Not assessed: no exact-variant reputable benign or likely benign assertion is available; the identified expert-panel classification is Pathogenic. Details ▾Hide ▴
Reasoning

BP6 cannot be assessed because no reputable source reports this exact variant as benign or likely benign. The available ClinVar expert-panel classification is Pathogenic, not benign, and no benign expert-panel assertion was identified.

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 record 7129 reports the exact variant as Pathogenic by the CFTR2 expert panel and provides no benign or likely benign expert-panel assertion.
Still missing
  • An exact-variant reputable benign or likely benign source report, with evidence unavailable for independent evaluation, would be needed to assess BP6.
Sources
Not applicable · 10· recorded as not applicable Show reasons ▾Hide reasons ▴
PS1 N/ANot applicable: PS1 requires a missense variant, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PM1 N/ANot applicable: PM1 requires a missense variant, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PM4 N/ANot applicable: PM4 requires a protein-length change, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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_stop_loss_or_nonrepeat_indel
Evidence considered
  • Deterministic consequence classification: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
pvs1_generic_framework ↗generic_acmg_combination_rules
PM5 N/ANot applicable: PM5 requires a missense variant, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PP2 N/ANot applicable: PP2 requires a missense variant, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
PP3 N/ANot applicable: c.3846G>A is a nonsense, protein-truncating variant outside the generic PP3 missense or splice-region/intronic scope. Details ▾Hide ▴
Reasoning

PP3 is not applicable because NM_000492.4:c.3846G>A is a nonsense variant producing p.(Trp1282Ter), a protein-length-changing truncating consequence outside the generic PP3 scope. The applicability decision is made before predictor review; therefore the available SpliceAI result and the BayesDel score are not used for PP3.

Rule
PP3/BP4 apply only to a missense variant, or to a splice-region/intronic variant via the SpliceAI path - never to a frameshift, nonsense, or other truncating/protein-length-changing variant.
Evidence considered
  • Case normalization identifies NM_000492.4:c.3846G>A as NP_000483.3:p.(Trp1282Ter), consequence class nonsense.
BP1 N/ANot applicable: BP1 requires a missense variant, and this is a nonsense variant. Details ▾Hide ▴
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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules
BP3 N/ANot applicable: BP3 requires an in-frame indel in a repeat region, and this is a nonsense variant. Details ▾Hide ▴
Reasoning

BP3 (Richards et al. 2015, PMID:25741868) applies to in-frame insertions/deletions located in a repetitive region without a known function. NM_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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_repeat_region_indel
Evidence considered
  • Deterministic consequence classification: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
pvs1_generic_framework ↗generic_acmg_combination_rules
BP4 N/ANot applicable: c.3846G>A is a nonsense, protein-truncating variant, so a no-splice-impact prediction cannot support generic BP4. Details ▾Hide ▴
Reasoning

BP4 is not applicable because NM_000492.4:c.3846G>A is a nonsense variant producing p.(Trp1282Ter), a protein-length-changing truncating consequence outside the generic BP4 scope. A no-splice-impact prediction cannot establish no impact on the gene product when the variant itself truncates the protein, so the available SpliceAI result is not used for BP4.

Rule
PP3/BP4 apply only to a missense variant, or to a splice-region/intronic variant via the SpliceAI path - never to a frameshift, nonsense, or other truncating/protein-length-changing variant.
Evidence considered
  • Case normalization identifies NM_000492.4:c.3846G>A as NP_000483.3:p.(Trp1282Ter), consequence class nonsense.
BP7 N/ANot applicable: BP7 requires a synonymous variant, and this is a nonsense 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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (prefetch.json normalized protein consequence)
  • VCEP criterion policy: absent
Sources
generic_acmg_combination_rules

Identifiers

Gene
CFTR
Transcript
NM_000492.4
Coding (HGVS c.)
NM_000492.4:c.3846G>A
Protein (HGVS p.)
NP_000483.3:p.(Trp1282Ter)
GRCh38
chr7:117642566 G>A
GRCh37
chr7:117282620 G>A
Location and type
Exon 23 · nonsense
ClinVar
1300168, 7129, 53983, 53456
COSMIC
COSV99069637

Gene diagram

Every interpreted variant in CFTR, mapped onto the exon structure of NM_000492.4. Select a row to find it on the plot.

CFTRNM_000492.4
Fetching transcript structure from UCSC…
gnomAD v4.1 421 / 1,613,376 alleles AF 0.000261 · 1 homozygotes · FAF 6.31e-05
gnomAD v2.1 121 / 282,282 alleles AF 0.000429 · 0 homozygotes · FAF 8.83e-05
gnomAD-Canada v1.0 Allele count data not recorded

By genetic ancestry

gnomAD v4.1

AF 0.00026 · 421 / 1,613,376 alleles · 1 hom · FAF 6.3e-05
Ashkenazi Jewish279 / 29,578 0.00941 hom
Remaining individuals48 / 62,450 0.00077
Middle Eastern1 / 6,078 0.00016
European (non-Finnish)90 / 1,179,672 7.6e-05
Admixed American2 / 59,928 3.3e-05
African/African American1 / 74,882 1.3e-05
0 alternate alleles recorded in 4 other groups: European (Finnish), Amish, East Asian, South Asian.

gnomAD v2.1

AF 0.00043 · 121 / 282,282 alleles · 0 hom · FAF 8.8e-05
Ashkenazi Jewish100 / 10,360 0.0097
Remaining individuals3 / 7,210 0.00042
European (non-Finnish)18 / 128,888 0.00014
0 alternate alleles recorded in 5 other groups: African/African American, Admixed American, East Asian, European (Finnish), South Asian.

Statements

gnomAD v4.1

This variant is present in gnomAD v4.1 (AF= 0.000260944; MAF= 0.02609%, 421/1613376 alleles, homozygotes = 1) and has highest observed frequency in the Ashkenazi Jewish population (AF= 0.00943269; MAF= 0.94327%, 279/29578 alleles, homozygotes = 1); grpmax FAF= 6.312e-05.

gnomAD v2.1

This variant is present in gnomAD v2.1 (AF= 0.000428649; MAF= 0.04286%, 121/282282 alleles, homozygotes = 0) and has highest observed frequency in the Ashkenazi Jewish population (AF= 0.00965251; MAF= 0.96525%, 100/10360 alleles, homozygotes = 0); grpmax FAF= 8.828e-05.

gnomAD-Canada

Not available in gnomAD-Canada v1.0.

SpliceAI and Pangolin

SpliceAI acceptor lossat -128 bp
0.014
SpliceAI acceptor gainat -321 bp
0.000
SpliceAI donor lossat +27 bp
0.014
SpliceAI donor gainat -35 bp
0.001

Other predictors

REVEL
Not available
BayesDel
0.660

How the predictions were used

PP3 N/ANot applicable: c.3846G>A is a nonsense, protein-truncating variant outside the generic PP3 missense or splice-region/intronic scope. Details ▾Hide ▴
Reasoning

PP3 is not applicable because NM_000492.4:c.3846G>A is a nonsense variant producing p.(Trp1282Ter), a protein-length-changing truncating consequence outside the generic PP3 scope. The applicability decision is made before predictor review; therefore the available SpliceAI result and the BayesDel score are not used for PP3.

Rule
PP3/BP4 apply only to a missense variant, or to a splice-region/intronic variant via the SpliceAI path - never to a frameshift, nonsense, or other truncating/protein-length-changing variant.
Evidence considered
  • Case normalization identifies NM_000492.4:c.3846G>A as NP_000483.3:p.(Trp1282Ter), consequence class nonsense.
BP4 N/ANot applicable: c.3846G>A is a nonsense, protein-truncating variant, so a no-splice-impact prediction cannot support generic BP4. Details ▾Hide ▴
Reasoning

BP4 is not applicable because NM_000492.4:c.3846G>A is a nonsense variant producing p.(Trp1282Ter), a protein-length-changing truncating consequence outside the generic BP4 scope. A no-splice-impact prediction cannot establish no impact on the gene product when the variant itself truncates the protein, so the available SpliceAI result is not used for BP4.

Rule
PP3/BP4 apply only to a missense variant, or to a splice-region/intronic variant via the SpliceAI path - never to a frameshift, nonsense, or other truncating/protein-length-changing variant.
Evidence considered
  • Case normalization identifies NM_000492.4:c.3846G>A as NP_000483.3:p.(Trp1282Ter), consequence class nonsense.
BP7 N/ANot applicable: BP7 requires a synonymous variant, and this is a nonsense 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_000492.4:c.3846G>A in CFTR is a nonsense substitution introducing a premature stop codon predicted to produce NP_000483.3:p.(Trp1282Ter). 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 CFTR, 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: nonsense (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 = 0.66.

9 paper records listed. 3 cited in the classification.

Cited in the classification

  • Cystic fibrosis population carrier screening: 2004 revision of American College of Medical Genetics mutation panel.
    Watson MS et al. · 2004 Sep-Oct
    The paper explicitly reports the CFTR nonsense variant W1282X, corresponding to c.3846G>A and NP_000483.3:p.(W1282*), among CF patient chromosomes, confirming the variant identity and its established occurrence in clinically diagnosed cystic fibrosis.
    → PVS1 · very strong → PS4 · strong Names this variant
    PMID 15371902 ↗
    Source detail
    W1282X 1.50 0.63 0.24 0.00 45.92 2.20

    Location Table 1, CFTR mutation frequency among individuals with clinically diagnosed cystic fibrosis by racial/ethnic group and in a pan-ethnic U.S. population

    Context Population-based mutation-frequency analysis of CF patient chromosomes using Cystic Fibrosis Foundation and Cystic Fibrosis Consortium databases; 42,737 CF patient chromosomes were analyzed for mutations not included in the original ACMG 25 panel.

  • Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene.
    The paper evaluates CFTR variants that introduce premature termination codons, including nonsense variants, and describes these variants as clinically deleterious and cystic-fibrosis-causing. It also relates CFTR premature-termination variants to nonsense-mediated decay with severe reduction of CFTR RNA and little or no protein production; this is gene-level mechanism evidence rather than a variant-specific result for W1282X.
    → PVS1 · very strong Does not name this variant
    PMID 23974870 ↗
    Source detail
    Thus, these 80 CFTR variants were predicted to be clinically deleterious4 and cystic fibrosis-causing

    Location Results, Functional analysis

    Context CFTR2 analysis of clinical and functional data from 39,696 individuals with cystic fibrosis; functional evaluation included CFTR RNA/protein processing and chloride-conductance assays, but no variant-specific result for c.3846G>A/p.(W1282*) is provided in the text.

  • Chemical modifications of adenine base editor mRNA and guide RNA expand its application scope.
    The paper explicitly describes CFTR W1282X, corresponding to c.3846G>A and NP_000483.3:p.(W1282*), in homozygous CFF-16HBEge bronchial epithelial cells. W1282X is described as an exon 23 G>A nonsense mutation producing minimal functional CFTR protein and abolishing chloride transport; base editing restored full-length CFTR expression and activity in the experimental model.
    → PVS1 · very strong → PS3 · supporting Names this variant
    PMID 32332735 ↗
    Source detail
    The second most common CFTR nonsense mutations, W1282X25,26, is caused by a G>A mutation in exon 23 that produces minimal amount of functional CFTR protein and abolishes its Cl− transport activity27. A previous report showed that the human bronchial epithelial cell line (CFF-16HBEge CFTR W1282X), homozygous for W1282X mutation, recapitulates the phenotype of primary W1282X CF cells25, making it a good cell model to study the correction of CFTR mutation.

    Location Results, “ABE corrects a nonsense mutation in cystic fibrosis model,” paragraph 1

    Context Homozygous CFF-16HBEge human bronchial epithelial cells carrying CFTR W1282X were evaluated for base editing, CFTR protein expression, clone genotypes, and CFTR-mediated chloride-channel activity.

Other recorded publications

  • Severe deficiency of cystic fibrosis transmembrane conductance regulator messenger RNA carrying nonsense mutations R553X and W1316X in respiratory epithelial cells of patients with cystic fibrosis.
    No paper-specific finding is recorded.
    PMID 1721624 ↗
  • Lumacaftor-Ivacaftor in Patients with Cystic Fibrosis Homozygous for Phe508del CFTR.
    No paper-specific finding is recorded.
    PMID 25981758 ↗
  • Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for ivacaftor therapy in the context of CFTR genotype.
    The paper does not explicitly mention CFTR c.3846G>A or NP_000483.3:p.(W1282*). It describes CFTR class I variants as biosynthesis defects, including premature-termination variants, and notes that such variants may potentially be treated with a suppressor in combination with ivacaftor. The paper does not provide variant-specific functional, clinical, segregation, or population data for p.(W1282*).
    Does not name this variant
    PMID 24598717 ↗
    Quoted passage
    Speculatively, ivacaftor may be effective in combination with a suppressor in patients with CFTR variants that affect biosynthesis of CFTR (i.e., resulting in premature termination codons).

    Linking CFTR genetic variants to ivacaftor effects in vitro and clinically, page 594

  • Pancreatitis Overview.
    No paper-specific finding is recorded.
    PMID 24624459 ↗
  • S737F is a new CFTR mutation typical of patients originally from the Tuscany region in Italy.
    No paper-specific finding is recorded.
    PMID 29298718 ↗
  • Cystic Fibrosis Foundation evidence-based guidelines for management of infants with cystic fibrosis.
    No paper-specific finding is recorded.
    PMID 19914445 ↗

Screenshots represent source records captured during evidence collection. Select one to view the recorded source content.

All source links

Statements for reports

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= 0.000260944; MAF= 0.02609%, 421/1613376 alleles, homozygotes = 1) and has highest observed frequency in the Ashkenazi Jewish population (AF= 0.00943269; MAF= 0.94327%, 279/29578 alleles, homozygotes = 1); grpmax FAF= 6.312e-05.

gnomAD v2.1

This variant is present in gnomAD v2.1 (AF= 0.000428649; MAF= 0.04286%, 121/282282 alleles, homozygotes = 0) and has highest observed frequency in the Ashkenazi Jewish population (AF= 0.00965251; MAF= 0.96525%, 100/10360 alleles, homozygotes = 0); grpmax FAF= 8.828e-05.

gnomAD-Canada

Not available in gnomAD-Canada v1.0.

ClinVar

This variant has been reported in ClinVar as Pathogenic (30 clinical laboratories) and as pathogenic (2 clinical laboratories) and as Pathogenic by CFTR2 (expert panel). (ClinVarID = 7129)

In silico

SpliceAI predicts no significant splice impact for this variant (max delta score = 0.01). BayesDel score = 0.66.

Somatic

This variant does not lie in a statistically significant hotspot. This variant has previously been reported in somatic cancers (COSMIC; COSV99069637, n = 1 times).

Cancer Hotspots

This variant does not lie in a statistically significant hotspot.