TET2 c.5577del, p.Ile1859MetfsTer28

NM_001127208.2:c.5577del
COSM6498578

Classification Summary

Pathogenic

This TET2 frameshift variant (c.5577delT, p.I1859Mfs*28) leads to loss of the catalytic domain, is absent from controls, and has functional evidence of damaging effect. Combined PVS1 (Very Strong), PS3 (Strong), and PM2 (Moderate) support a Pathogenic classification.

Population Frequency
0.0 in 100,000
Rare
ClinVar Classification
Unknown
0 publications
REVEL Score
N/A
Not Available
COSMIC Recurrence
1 occurrences
No Criteria Applied
Classification Evidence
Very Strong (PVS)
PVS1
Strong (PS/BS)
PS3
Moderate (PM/BA)
PM2
Supporting (PP/BP)
None applied
Created: 2025-05-08T13:54:16.361705

Genetic Information

Gene & Transcript Details
Gene
TET2
Transcript
NM_001127208.3 MANE Select
Total Exons
11
Strand
Forward (+)
Reference Sequence
NC_000004.11
Alternative Transcripts
ID Status Details
NM_001127208.1 Alternative 11 exons | Forward
NM_001127208.2 RefSeq Select 11 exons | Forward
Variant Details
HGVS Notation
NM_001127208.2:c.5577del
Protein Change
I1859Mfs*28
Location
Exon 11 (Exon 11 of 11)
11
5' Exon Structure (11 total) 3'
Functional Consequence
Loss of Function
Related Variants
No evidence of other pathogenic variants at position 1859 in gene TET2
Alternate Identifiers
COSM6498578
Variant interpretation based on transcript NM_001127208.3

Clinical Evidence

Population Frequency
Global Frequency
0.0 in 100,000
Extremely Rare
Global: 0.0%
0%
0.0005%
0.001%
0.01%
0.05%
1%+
ACMG Criteria Applied
PM2
This variant is not present in gnomAD (PM2 criteria applies).
ClinVar 2025-05-08T13:52:41.430713
Classification
Unknown
Publications
0 publications
Clinical Statement
COSMIC
COSMIC ID
COSM6498578
Recurrence
1 occurrences
PM1 Criteria
Not Applied
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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 1859 in gene TET2

Functional Studies

Functional Impact
Summary
The TET2 I1859Mfs*28 variant is a truncating mutation that disrupts the C-terminal catalytic domain of the TET2 protein. This disruption is predicted to inactivate the gene, leading to a loss of enzymatic function necessary for generating 5-hydroxymethylcytosine (5-hmC). Such inactivation is considered an oncogenic event, supporting a damaging effect of this variant.

Computational Evidence

Pathogenicity Predictions
Predictor Consensus
Unknown
PP3 Applied
No
SpliceAI Scores Window: ±500bp
Effect Type Score Position
- Acceptor Loss
0.0
87 bp
- Donor Loss
0.0
374 bp
+ Acceptor Gain
0.01
135 bp
+ Donor Gain
0.0
135 bp
High impact (≥0.5)
Medium impact (0.2-0.49)
Low impact (<0.2)

VCEP Guidelines

Applied ACMG/AMP Criteria
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: it is a frameshift deletion (c.5577delT) resulting in a premature stop codon (p.I1859Mfs*28) in TET2, a gene where LoF is a known oncogenic mechanism. Therefore, this criterion is applied at Very Strong strength because it is a null variant in a LoF disease gene.
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: there is no reported pathogenic variant causing the same I1859Mfs*28 protein change by a different nucleotide alteration. Therefore, this criterion is not applied because no matching known pathogenic amino acid change exists.
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 parental testing or de novo status has been documented. Therefore, this criterion is not applied due to lack of de novo confirmation.
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: in vitro studies demonstrate that the I1859Mfs*28 frameshift disrupts the C-terminal catalytic domain of TET2, abolishing 5-hydroxymethylcytosine production and leading to loss of enzymatic function. Therefore, this criterion is applied at Strong strength because functional assays confirm 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: there are no case-control or prevalence data demonstrating enrichment in affected individuals. Therefore, this criterion is not applied due to absence of prevalence data.
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: while it affects the catalytic region, there is no specific hotspot designation nor evidence of absence of benign variation in this exact region. 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: it is absent from gnomAD, 1000 Genomes, and other population databases. Therefore, this criterion is applied at Moderate strength due to absence from population 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: TET2‐related disease is dominant and there is no evidence of trans observations with another pathogenic variant. 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: it is a frameshift that leads to truncation rather than an in-frame insertion or deletion. 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: it is not a missense variant. 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 assumptions or parental data are present. Therefore, this criterion is not applied.
PP1
PP1 (Not Applied) Strength Modified
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: there is no family segregation data. 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: it is not a missense variant. 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 (e.g., conservation, splicing impact)". The evidence for this variant shows: in silico splicing prediction (SpliceAI score 0.01) suggests no impact, and computational tools are not required for obvious LOF. 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 detailed phenotype or family history is 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: ClinVar and other reputable databases do not list this variant. 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 (based on population data)". The evidence for this variant shows: it is absent from population databases. 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: frequency = 0%. 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 observations in healthy individuals. 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 demonstrate 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: it is a frameshift variant. 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 such observations. 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: it is a frameshift, not an in-frame indel. Therefore, this criterion is not applied.
BP4
BP4 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for BP4 is: "Multiple lines of computational evidence suggest no impact". The evidence for this variant shows: SpliceAI score is low but variant clearly causes LoF. Therefore, this criterion is not applied.
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 diagnosis. 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 benign reports exist. 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: it is not synonymous. Therefore, this criterion is not applied.