Genetic Information
Gene & Transcript Details
| ID | Status | Details |
|---|---|---|
| NM_004343.4 | MANE Select | 1901 nt | 72–1325 |
| NM_004343.2 | Alternative | 1899 nt | 69–1322 |
| NM_004343.3 | RefSeq Select | 1929 nt | 81–1334 |
Variant Details
Clinical & Population Data
Population Frequency
gnomADClinVar
Open""
COSMIC Somatic Evidence
Open
Functional Impact & Domains
Functional Domain
The CALR Q365Rfs*50 mutation has been functionally characterized as likely oncogenic. Truncating and frameshift mutations in CALR, such as this one, are associated with cytokine-independent growth in cell models and are prevalent in patients with myeloproliferative neoplasms lacking MPL or JAK2 mutations. These mutations result in novel, positively-charged C-terminal amino acids and are linked to an increased risk of myelofibrotic transformation.
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Computational Analysis
Pathogenicity Predictions
SpliceAISpliceAI Scores
Window: ±500bp| Effect Type | Score | Position |
|---|---|---|
| Acceptor Loss (AL) | 0.01 | -321 bp |
| Donor Loss (DL) | 0.0 | 236 bp |
| Acceptor Gain (AG) | 0.06 | -35 bp |
| Donor Gain (DG) | 0.0 | -303 bp |
VCEP Guidelines
Applied ACMG/AMP Criteria (VCEP Specific)
PVS1 (Very Strong)
According to standard ACMG guidelines, the rule for PVS1 is: "Null variant in a gene where loss of function (LoF) is a known mechanism of disease (e.g., nonsense, frameshift, canonical ±1 or 2 splice sites, initiation codon, single exon deletion in a LoF gene)". The evidence for this variant shows: it is a frameshift deletion leading to a premature stop codon (Q365Rfs*50) in CALR, a gene where LoF is an established disease mechanism. Therefore, this criterion is applied at Very Strong strength because it is a null variant in a LoF gene.
PS1 (Not Applied)
According to standard ACMG guidelines, the rule for PS1 is: "Same amino acid change as a known pathogenic variant but different nucleotide change". The evidence for this variant shows: this is a frameshift variant resulting in a novel protein sequence, not the same amino acid change as any known pathogenic variant. Therefore, this criterion is not applied.
PS2 (Not Applied)
According to standard ACMG guidelines, the rule for PS2 is: "De novo (both maternity and paternity confirmed) in a patient with the disease and no family history". The evidence for this variant shows: no information on de novo occurrence or parental testing is provided. Therefore, this criterion is not applied.
PS3 (Strong)
According to standard ACMG guidelines, the rule for PS3 is: "Well-established functional studies supportive of a damaging effect on the gene or gene product". The evidence for this variant shows: in vitro and in vivo studies characterize Q365Rfs*50 as oncogenic, conferring cytokine-independent growth and a novel positively-charged C-terminal domain linked to myeloproliferative neoplasia. Therefore, this criterion is applied at Strong strength because robust functional data demonstrate a damaging effect.
PS4 (Not Applied)
According to standard ACMG guidelines, the rule for PS4 is: "Prevalence in affected individuals significantly increased compared with controls". The evidence for this variant shows: no case-control or prevalence data quantifying enrichment in patients compared to controls. Therefore, this criterion is not applied.
PM1 (Not Applied)
According to standard ACMG guidelines, the rule for PM1 is: "Located in a mutational hot spot or well-established functional domain without benign variation". The evidence for this variant shows: exon information and hotspot status are unavailable. Therefore, this criterion is not applied.
PM2 (Moderate)
According to standard ACMG guidelines, the rule for PM2 is: "Absent from controls (or at extremely low frequency if recessive)". The evidence for this variant shows: variant not found in population databases including gnomAD. Therefore, this criterion is applied at Moderate strength because it is absent from large population cohorts.
PM3 (Not Applied)
According to standard ACMG guidelines, the rule for PM3 is: "Detected in trans with a pathogenic variant (for recessive disorders)". The evidence for this variant shows: CALR-associated disease is autosomal dominant and no trans data are relevant. Therefore, this criterion is not applied.
PM4 (Not Applied)
According to standard ACMG guidelines, the rule for PM4 is: "Protein length changes due to in-frame deletions/insertions or stop-loss variants". The evidence for this variant shows: it is a frameshift leading to truncation rather than an in-frame change or stop-loss. Therefore, this criterion is not applied.
PM5 (Not Applied)
According to standard ACMG guidelines, the rule for PM5 is: "Novel missense change at an amino acid residue where a different pathogenic missense change has been seen". The evidence for this variant shows: it is a frameshift, not a missense change. Therefore, this criterion is not applied.
PM6 (Not Applied)
According to standard ACMG guidelines, the rule for PM6 is: "Assumed de novo, but without confirmation of paternity and maternity". The evidence for this variant shows: no de novo assumption data are provided. Therefore, this criterion is not applied.
PP1 (Not Applied)
According to standard ACMG guidelines, the rule for PP1 is: "Co-segregation with disease in multiple affected family members". The evidence for this variant shows: no segregation data available. Therefore, this criterion is not applied.
PP2 (Not Applied)
According to standard ACMG guidelines, the rule for PP2 is: "Missense variant in a gene with a low rate of benign missense variation and where missense variants are a common mechanism of disease". The evidence for this variant shows: it is a frameshift, not a missense variant. Therefore, this criterion is not applied.
PP3 (Not Applied)
According to standard ACMG guidelines, the rule for PP3 is: "Multiple lines of computational evidence support a deleterious effect on the gene/gene product (e.g., conservation, splicing impact)". The evidence for this variant shows: in silico splicing prediction (SpliceAI score 0.06) is below pathogenic thresholds and no other computational evidence of deleteriousness. Therefore, this criterion is not applied.
PP4 (Not Applied)
According to standard ACMG guidelines, the rule for PP4 is: "Patient's phenotype or family history highly specific for a disease with a single genetic etiology". The evidence for this variant shows: no phenotype or clinical context provided. Therefore, this criterion is not applied.
PP5 (Not Applied)
According to standard ACMG guidelines, the rule for PP5 is: "Reputable source reports variant as pathogenic, but without accessible evidence". The evidence for this variant shows: not found in ClinVar or other reputable databases. Therefore, this criterion is not applied.
BA1 (Not Applied)
According to standard ACMG guidelines, the rule for BA1 is: "Allele frequency is too high for the disorder". The evidence for this variant shows: allele frequency is 0% in gnomAD, not above threshold. Therefore, this criterion is not applied.
BS1 (Not Applied)
According to standard ACMG guidelines, the rule for BS1 is: "Allele frequency is greater than expected for the disorder". The evidence for this variant shows: absent from population databases. Therefore, this criterion is not applied.
BS2 (Not Applied)
According to standard ACMG guidelines, the rule for BS2 is: "Observed in healthy individuals with full penetrance expected at an early age". The evidence for this variant shows: no observations in healthy individuals are reported. Therefore, this criterion is not applied.
BS3 (Not Applied)
According to standard ACMG guidelines, the rule for BS3 is: "Well-established functional studies show no damaging effect on protein function or splicing". The evidence for this variant shows: functional studies demonstrate damaging, oncogenic effect. Therefore, this criterion is not applied.
BS4 (Not Applied)
According to standard ACMG guidelines, the rule for BS4 is: "Lack of segregation in affected family members". The evidence for this variant shows: no segregation data. Therefore, this criterion is not applied.
BP1 (Not Applied)
According to standard ACMG guidelines, the rule for BP1 is: "Missense variant in a gene where only LoF causes disease". The evidence for this variant shows: it is not a missense variant. Therefore, this criterion is not applied.
BP2 (Not Applied)
According to standard ACMG guidelines, the rule for BP2 is: "Observed in trans with a pathogenic variant for dominant disorders or in cis with a pathogenic variant". The evidence for this variant shows: no such observations. Therefore, this criterion is not applied.
BP3 (Not Applied)
According to standard ACMG guidelines, the rule for BP3 is: "In-frame deletions/insertions in a repetitive region without known function". The evidence for this variant shows: it is a frameshift deletion leading to truncation, not an in-frame change. Therefore, this criterion is not applied.
BP4 (Not Applied)
According to standard ACMG guidelines, the rule for BP4 is: "Multiple lines of computational evidence suggest no impact". The evidence for this variant shows: only SpliceAI data below threshold; no broader computational benign evidence. Therefore, this criterion is not applied.
BP5 (Not Applied)
According to standard ACMG guidelines, the rule for BP5 is: "Variant found in a case with an alternate molecular basis for disease". The evidence for this variant shows: no such case-level context. Therefore, this criterion is not applied.
BP6 (Not Applied)
According to standard ACMG guidelines, the rule for BP6 is: "Reputable source reports variant as benign, but without accessible evidence". The evidence for this variant shows: no benign reports found. Therefore, this criterion is not applied.
BP7 (Not Applied)
According to standard ACMG guidelines, the rule for BP7 is: "Synonymous variant with no predicted impact on splicing". The evidence for this variant shows: it is a frameshift, not synonymous. Therefore, this criterion is not applied.