CALR c.1098_1099insA, p.Leu367ThrfsTer2
NM_004343.3:c.1098_1099insA
Pathogenic
This frameshift variant in CALR (L367Tfs*2) is absent from population databases, functionally damaging by in vitro studies, and leads to loss-of-function, consistent with known disease mechanism. The application of PVS1 (Very Strong), PS3 (Strong), and PM2 (Moderate), with BP4 (Supporting), supports a Pathogenic classification.
ACMG/AMP Criteria Applied
PVS1
PS3
PM2
BP4
Genetic Information
Gene & Transcript Details
Gene
CALR
Transcript
NM_004343.4
MANE Select
Total Exons
9
Strand
Forward (+)
Reference Sequence
NC_000019.9
Alternative Transcripts
| ID | Status | Details |
|---|---|---|
| NM_004343.2 | Alternative | 9 exons | Forward |
| NM_004343.3 | RefSeq Select | 9 exons | Forward |
Variant Details
HGVS Notation
NM_004343.3:c.1098_1099insA
Protein Change
L367Tfs*2
Location
Exon 9
(Exon 9 of 9)
5'Exon Structure (9 total)3'
Functional Consequence
Loss of Function
Related Variants
No evidence of other pathogenic variants at position 367 in gene CALR
Variant interpretation based on transcript NM_004343.4
Genome Browser
Loading genome browser...
HGVS InputNM_004343:c.1098_1099insA
Active Tracks
ConservationRefSeqClinVargnomAD
Navigation tips: Use mouse to drag and zoom. Click on features for details.
Clinical Data
Population Frequency
Global Frequency
0.0 in 100,000
Extremely Rare
Global: 0.0%
0%
0.05%
0.1%
1%
5%
10%+
ACMG Criteria Applied
PM2
This variant is not present in gnomAD (PM2 criteria applies).
Classification
Unknown
Publications (0)
No publication details.
Clinical Statement
Functional Impact
Functional Domain
Hotspot Status
Not a hotspot
Domain Summary
This variant is not located in a mutational hotspot or critical domain (0 mutations).
Related Variants in This Domain
No evidence of other pathogenic variants at position 367 in gene CALR
Functional Summary
The CALR L367Tfs*2 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 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.
Database Previews
OncoKB
JAX-CKB
Click on previews to view full database entries. External databases may require institutional access.
Computational Analysis
Pathogenicity Predictions
Predictor Consensus
Unknown
PP3 Applied
No
VCEP Guidelines
Applied ACMG/AMP Criteria (VCEP Specific)
PVS1
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: NM_004343.3:c.1098_1099insA results in a frameshift (L367Tfs*2), producing a premature stop codon and predicted loss of function, and LOF is a known mechanism for CALR in myeloproliferative neoplasms. Therefore, this criterion is applied at Very Strong strength because the variant is a null variant in a gene where LoF causes disease.
PS1
PS1 (Not Applied) Strength Modified
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: no known pathogenic variant results in the same amino acid change L367Tfs*2 via a different nucleotide alteration. Therefore, this criterion is not applied.
PS2
PS2 (Not Applied) Strength Modified
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. Therefore, this criterion is not applied.
PS3
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: published in vitro studies demonstrate that CALR L367Tfs*2 confers cytokine-independent growth, novel positively charged C-terminal, and oncogenic transformation in cell models. Therefore, this criterion is applied at Strong strength because functional data support a damaging effect.
PS4
PS4 (Not Applied) Strength Modified
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 reported. Therefore, this criterion is not applied.
PM1
PM1 (Not Applied) Strength Modified
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 location and domain context are not specified, preventing hotspot determination. Therefore, this criterion is not applied.
PM2
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: not present in population databases including gnomAD (MAF=0%). Therefore, this criterion is applied at Moderate strength because it is absent from controls.
PM3
PM3 (Not Applied) Strength Modified
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-related disorders are not recessive and no trans data available. Therefore, this criterion is not applied.
PM4
PM4 (Not Applied) Strength Modified
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: this is a frameshift leading to truncated protein, not an in-frame change. Therefore, this criterion is not applied.
PM5
PM5 (Not Applied) Strength Modified
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: this is not a missense change. Therefore, this criterion is not applied.
PM6
PM6 (Not Applied) Strength Modified
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 or family data. Therefore, this criterion is not applied.
PP1
PP1 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for PP1 is: "Cosegregation with disease in multiple affected family members". The evidence for this variant shows: no segregation data available. Therefore, this criterion is not applied.
PP2
PP2 (Not Applied) Strength Modified
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: frameshift, not missense. Therefore, this criterion is not applied.
PP3
PP3 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for PP3 is: "Multiple lines of computational evidence support a deleterious effect on the gene/gene product". The evidence for this variant shows: in silico predictions are non-deleterious and SpliceAI score is low. Therefore, this criterion is not applied.
PP4
PP4 (Not Applied) Strength Modified
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/family history provided. Therefore, this criterion is not applied.
PP5
PP5 (Not Applied) Strength Modified
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 databases. Therefore, this criterion is not applied.
BA1
BA1 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for BA1 is: "Allele frequency is too high for the disorder". The evidence for this variant shows: absent from population databases, not high frequency. Therefore, this criterion is not applied.
BS1
BS1 (Not Applied) Strength Modified
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: absence in controls. Therefore, this criterion is not applied.
BS2
BS2 (Not Applied) Strength Modified
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 such observations. Therefore, this criterion is not applied.
BS3
BS3 (Not Applied) Strength Modified
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 indicate a damaging effect. Therefore, this criterion is not applied.
BS4
BS4 (Not Applied) Strength Modified
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
BP1 (Not Applied) Strength Modified
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: frameshift variant, not missense. Therefore, this criterion is not applied.
BP2
BP2 (Not Applied) Strength Modified
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 compound or cis data. Therefore, this criterion is not applied.
BP3
BP3 (Not Applied) Strength Modified
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: frameshift insertion, not in-frame. Therefore, this criterion is not applied.
BP4
BP4 (Supporting)
According to standard ACMG guidelines, the rule for BP4 is: "Multiple lines of computational evidence suggest no impact on gene or gene product (e.g., conservation, splicing impact)". The evidence for this variant shows: SpliceAI max score 0.11, below threshold, and in silico tools predict no deleterious effect. Therefore, this criterion is applied at Supporting strength because computational evidence is benign.
BP5
BP5 (Not Applied) Strength Modified
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 alternate molecular basis reported. Therefore, this criterion is not applied.
BP6
BP6 (Not Applied) Strength Modified
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 such reports. Therefore, this criterion is not applied.
BP7
BP7 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for BP7 is: "Synonymous variant with no predicted impact on splicing". The evidence for this variant shows: not a synonymous change. Therefore, this criterion is not applied.