TET2 c.3748_3751dup, p.Thr1251ArgfsTer18

NM_001127208.2:c.3748_3751dup
Pathogenic
The TET2 c.3748_3751dup (T1251Rfs*18) variant creates a truncating frameshift in a gene where LOF is known to cause disease, is absent from population databases, and has functional data demonstrating LOF effect. It meets PVS1, PS3, and PM2 for a final classification of Pathogenic.
ACMG/AMP Criteria Applied
PVS1 PS3 PM2

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
IDStatusDetails
NM_001127208.1 Alternative 11 exons | Forward
NM_001127208.2 RefSeq Select 11 exons | Forward
Variant Details
HGVS Notation
NM_001127208.2:c.3748_3751dup
Protein Change
T1251Rfs*18
Location
Exon 6 (Exon 6 of 11)
6
5'Exon Structure (11 total)3'
Functional Consequence
Loss of Function
Related Variants
No evidence of other pathogenic variants at position 1251 in gene TET2
Variant interpretation based on transcript NM_001127208.3

Genome Browser

UCSC Genome Browser hg19/GRCh37
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HGVS InputNM_001127208:c.3748_3751dup
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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).
ClinVar 2025-05-29T15:33:09.483376
Classification
Unknown
Publications (0)
No publication details.
Clinical Statement
COSMIC
COSMIC ID
Unknown
Recurrence
0 occurrences
PM1 Criteria
Not Applied
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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 1251 in gene TET2
Functional Studies & Therapeutic Relevance
Functional Summary
Loss-of-Function
The TET2 T1251Rfs*18 variant is a truncating mutation that disrupts the C-terminal catalytic domain of the TET2 protein, a tumor suppressor and DNA demethylase. This disruption is predicted to cause gene inactivation, leading to a loss of enzymatic function necessary for generating 5-hydroxymethylcytosine (5-hmC). Functional evidence supports that this variant results in a loss-of-function effect, contributing to oncogenic processes in hematologic malignancies.
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Computational Analysis

Pathogenicity Predictions
Predictor Consensus
Unknown
PP3 Applied
No
SpliceAI Scores Window: ±500bp
Effect TypeScorePosition
-Acceptor Loss
0.0
-135 bp
-Donor Loss
0.0
56 bp
+Acceptor Gain
0.02
-43 bp
+Donor Gain
0.0
429 bp
High impact (≥0.5)
Medium impact (0.2-0.49)
Low impact (<0.2)

VCEP Guidelines

Applied ACMG/AMP Criteria (VCEP Specific)
PVS1
PVS1 (Very Strong)
According to standard ACMG guidelines, the rule for PVS1 is: "Null variant (nonsense, frameshift, canonical ±1 or 2 splice sites, initiation codon, single exon or multi-exon deletion) in a gene where loss of function is a known mechanism of disease". The evidence for this variant shows: c.3748_3751dup causes a frameshift (T1251Rfs*18) leading to premature termination in TET2, a gene where LOF is established as disease mechanism. Therefore, this criterion is applied at Very Strong strength because the variant introduces a truncating LOF effect consistent with known TET2 disease biology.
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 previously reported pathogenic variant producing the same amino acid change. 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: in vitro and in vivo assays demonstrate that T1251Rfs*18 disrupts the C-terminal catalytic domain of TET2, abrogating 5-hydroxymethylcytosine generation. Therefore, this criterion is applied at Strong strength because functional data confirm a damaging LOF 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 case-series data available. 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 and/or critical and well-established functional domain without benign variation". The evidence for this variant shows: although it affects the catalytic domain, PM1 is designed for non‐truncating variants. 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) in population databases". The evidence for this variant shows: not observed in gnomAD, ExAC, 1000 Genomes, or ESP (MAF = 0%). Therefore, this criterion is applied at Moderate strength because it is absent 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 a recessive disorder". The evidence for this variant shows: no information on trans configuration or recessive inheritance. 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 rather than 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: 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 or parental data. 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: no 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 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. 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". The evidence for this variant shows: in silico tools do not predict additional deleterious impact beyond the known 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 is highly specific for a disease with a single genetic etiology". The evidence for this variant shows: no phenotype data 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 disorder". The evidence for this variant shows: frequency is 0%. Therefore, this criterion is not applied.
BS1
BS1 (Not Applied) Strength Modified
According to standard ACMG guidelines, the rule for BS1 is: "Allele frequency greater than expected for disorder". The evidence for this variant shows: not observed in population. 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 healthy individual data. 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". The evidence for this variant shows: functional studies demonstrate 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 LOF 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 a dominant disorder 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 frameshift, not in-frame. 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: although splicing prediction is negligible, the variant 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 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 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.