rs370502517
Variant summary
Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. BP4PM2_SupportingPP4BS2
This summary comes from the ClinGen Evidence Repository: The NM_000546.6: c.149T>C variant in TP53 is a missense variant predicted to cause substitution of Isoleucine by Threonine at amino acid 50 (p.Ile50Thr). This variant has been observed in 4-7 heterozygous unrelated females from the same data source with no personal history of cancer prior to age 60 years and no personal history of sarcoma at any age (BS2_Moderate; Internal lab contributor: LabCorp Genetics). At least one individual with this variant was found to have a variant allele fraction of 5-35%, which is a significant predictor of variant pathogenicity (PP4, PMID:34906512, Internal lab contributor: LabCorp Genetics). This variant has an allele frequency of 0.000001239 (2/1614026 alleles) across gnomAD v4.1.0 which is lower than the Clingen TP53 VCEP threshold (<0.00003) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). In vitro assays performed in yeast and/or human cell lines showed partially functional transactivation and retained growth suppression activity indicating that this variant does not impact protein function; however a third assay corroborating these findings was not available (BS3_Supporting not met; PMIDs: 12826609, 30224644). Computational predictor scores (BayesDel = -0.0655; Align GVGD Class C0) are below the recommended thresholds (BayesDel ≤ -0.008 and an Align GVGD Class ≤ 55), evidence that does not predict a damaging effect on TP53 via protein change. SpliceAI predicts that the variant has no impact on splicing. (BP4_Moderate). In summary, this variant meets the criteria to be classified as Likely Benign for Li Fraumeni syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen TP53 VCEP: BS2_Moderate, PP4, PM2_Supporting, BP4_Moderate. (Bayesian Points: -2; VCEP specifications version 2.1.0; 1/16/2025) LINK:https://erepo.genome.network/evrepo/ui/classification/CA337284/MONDO:0018875/009
Frequency
Consequence
NM_000546.6 missense
Scores
Clinical Significance
Conservation
Publications
- breast cancerInheritance: AD Classification: DEFINITIVE Submitted by: Ambry Genetics
- Li-Fraumeni syndromeInheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Orphanet
- Li-Fraumeni syndrome 1Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp
- adrenocortical carcinoma, hereditaryInheritance: AD Classification: STRONG Submitted by: Ambry Genetics
- sarcomaInheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
- bone marrow failure syndrome 5Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
- colorectal cancerInheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
- choroid plexus carcinomaInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
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ACMG classification
Our verdict: Likely_benign. The variant received -3 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000657 AC: 1AN: 152144Hom.: 0 Cov.: 31 show subpopulations
GnomAD4 exome AF: 6.84e-7 AC: 1AN: 1461882Hom.: 0 Cov.: 56 AF XY: 0.00000138 AC XY: 1AN XY: 727246 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.00000657 AC: 1AN: 152144Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0AN XY: 74322 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
Li-Fraumeni syndrome Uncertain:2Benign:1
The NM_000546.6: c.149T>C variant in TP53 is a missense variant predicted to cause substitution of Isoleucine by Threonine at amino acid 50 (p.Ile50Thr). This variant has been observed in 4-7 heterozygous unrelated females from the same data source with no personal history of cancer prior to age 60 years and no personal history of sarcoma at any age (BS2_Moderate; Internal lab contributor: LabCorp Genetics). At least one individual with this variant was found to have a variant allele fraction of 5-35%, which is a significant predictor of variant pathogenicity (PP4, PMID: 34906512, Internal lab contributor: LabCorp Genetics). This variant has an allele frequency of 0.000001239 (2/1614026 alleles) across gnomAD v4.1.0 which is lower than the Clingen TP53 VCEP threshold (<0.00003) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). In vitro assays performed in yeast and/or human cell lines showed partially functional transactivation and retained growth suppression activity indicating that this variant does not impact protein function; however a third assay corroborating these findings was not available (BS3_Supporting not met; PMIDs: 12826609, 30224644). Computational predictor scores (BayesDel = -0.0655; Align GVGD Class C0) are below the recommended thresholds (BayesDel ≤ -0.008 and an Align GVGD Class ≤ 55), evidence that does not predict a damaging effect on TP53 via protein change. SpliceAI predicts that the variant has no impact on splicing. (BP4_Moderate). In summary, this variant meets the criteria to be classified as Likely Benign for Li Fraumeni syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen TP53 VCEP: BS2_Moderate, PP4, PM2_Supporting, BP4_Moderate. (Bayesian Points: -2; VCEP specifications version 2.1.0; 1/16/2025) -
This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 50 of the TP53 protein (p.Ile50Thr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with acute lymphoblastic leukemia (PMID: 26580448). ClinVar contains an entry for this variant (Variation ID: 216464). Advanced modeling performed at Invitae incorporating data from internal and/or published experimental studies (PMID: 12826609, 29979965, 30224644) indicates that this missense variant is expected to disrupt TP53 function with a positive predictive value of 97.5%. Experimental studies have shown that this missense change does not substantially affect TP53 function (PMID: 12826609, 30224644). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
This missense variant replaces isoleucine with threonine at codon 50 of the TP53 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). Experimental studies have shown that this variant is partially functional in yeast transactivation assays (PMID: 12826609) and exhibited normal function in human cell growth suppression assays (PMID: 30224644). This variant has been reported in an individual affected with B-lineage acute lymphoblastic leukemia (PMID: 26580448). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Li-Fraumeni syndrome 1 Uncertain:2
This variant is classified as a variant of uncertain significance as there is insufficient evidence to determine its impact on protein function and/or cancer risk. -
This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -
Hereditary cancer-predisposing syndrome Uncertain:1
The p.I50T variant (also known as c.149T>C), located in coding exon 3 of the TP53 gene, results from a T to C substitution at nucleotide position 149. The isoleucine at codon 50 is replaced by threonine, an amino acid with similar properties. This variant has been reported in 1/1120 pediatric cancer patients who underwent whole genome sequencing; this patient was diagnosed with acute lymphocytic leukemia (Zhang J et al. N. Engl. J. Med. 2015 Dec;373(24):2336-2346). This variant is in the transactivation domain of the TP53 protein and is reported to have a partial loss of transactivation capacity in yeast based assays (IARC TP53 database; Kato S et al. Proc Natl Acad Sci USA. 2003 Jul 8;100(14):8424-9). Studies conducted in human cell lines indicate this alteration remains proficient at growth suppression (Giacomelli AO et al. Nat. Genet. 2018 Oct;50:1381-1387). This amino acid position is poorly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at