rs587781433

Variant names:

• chr17-7674197-T-C
• rs587781433
• NM_000546.6:c.766A>G

Your query was ambiguous. Multiple possible variants found:

• chr17-7674197-T-C
• chr17-7674197-T-G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000546.6(TP53):​c.766A>G​(p.Thr256Ala) variant causes a missense change. The variant allele was found at a frequency of 0.000000685 in 1,460,386 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T256P) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TP53 NM_000546.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 6.24
• Publications: 55 publications found

Genes affected

TP53 (HGNC:11998): (tumor protein p53) This gene encodes a tumor suppressor protein containing transcriptional activation, DNA binding, and oligomerization domains. The encoded protein responds to diverse cellular stresses to regulate expression of target genes, thereby inducing cell cycle arrest, apoptosis, senescence, DNA repair, or changes in metabolism. Mutations in this gene are associated with a variety of human cancers, including hereditary cancers such as Li-Fraumeni syndrome. Alternative splicing of this gene and the use of alternate promoters result in multiple transcript variants and isoforms. Additional isoforms have also been shown to result from the use of alternate translation initiation codons from identical transcript variants (PMIDs: 12032546, 20937277). [provided by RefSeq, Dec 2016]

TP53 Gene-Disease associations (from GenCC):

• breast cancer

  Inheritance: AD Classification: DEFINITIVE Submitted by: Ambry Genetics
• Li-Fraumeni syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen, Orphanet
• Li-Fraumeni syndrome 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Genomics England PanelApp
• adrenocortical carcinoma, hereditary

  Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics
• sarcoma

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• bone marrow failure syndrome 5

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
• colorectal cancer

  Inheritance: AD Classification: MODERATE Submitted by: Ambry Genetics
• choroid plexus carcinoma

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 41 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 7 benign, 31 uncertain in NM_000546.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-7674197-T-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 528269.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TP53	NM_000546.6	c.766A>G	p.Thr256Ala	missense_variant	Exon 7 of 11	ENST00000269305.9	NP_000537.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TP53	ENST00000269305.9	c.766A>G	p.Thr256Ala	missense_variant	Exon 7 of 11	1	NM_000546.6	ENSP00000269305.4

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460386 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726586

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33444

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26122

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86230

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1110642

Other (OTH) AF: 0.00 AC: 0 AN: 60344

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 30

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Sep 20, 2021

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces threonine with alanine at codon 256 of the TP53 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). Functional analysis in yeast reported transcriptional activity for this variant (PMID: 16861262) with reduced activity in one study (PMID: 12826609). This variant has been reported in an individual affected with Li-Fraumeni syndrome (PMID: 20127978). 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. -

Jan 04, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T256A variant (also known as c.766A>G) is located in coding exon 6 of the TP53 gene. This alteration results from an A to G substitution at nucleotide position 766. The threonine at codon 256 is replaced by alanine, an amino acid with similar properties. This has been identified in a patient reported to have Li-Fraumeni syndrome; however clinical details were not provided (Morgan JE et al. Hum Mutat. 2010 Apr;31(4):484-91). This alteration has been observed in at least one individual with a personal and/or family history that is consistent with TP53-related disease; however, it has also been seen in individuals with cancer diagnoses at later age of onset than expected for TP53-related disease (Ambry internal data, personal communication). This variant is in the DNA binding domain of the TP53 protein and is reported to have partially functional transactivation in yeast based assays (Kato S et al. Proc. Natl. Acad. Sci. USA. 2003 Jul;100:8424-9). However, studies conducted in human cell lines indicate this alteration is proficient at growth suppression and has no dominant negative effect (Kotler E et al. Mol.Cell. 2018 Jul;71:178-190.e8; Giacomelli AO et al. Nat. Genet. 2018 Oct;50:1381-1387). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on current evidence, this alteration may be a moderate risk allele that leads to increased risk of developing a TP53-related cancer; however, since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Li-Fraumeni syndrome Uncertain:1

Feb 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 256 of the TP53 protein (p.Thr256Ala). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of Li-Fraumeni syndrome (PMID: 20127978). ClinVar contains an entry for this variant (Variation ID: 141011). 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, 16861262, 29979965, 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. -

Li-Fraumeni syndrome 1 Uncertain:1

Oct 30, 2014

Pathway Genomics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;D;.;.;.;.;T;T;.;D;.;.;.;.;.;.;D;.;.;.
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;.;.;.;D;D;.;D;D;D;D;D;D
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	2.9	.;.;.;.;.;.;.;.;.;M;.;M;M;M;.;.;M;.;.;.
PhyloP100		6.2
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-4.4	D;D;.;.;.;.;.;.;.;D;.;.;D;D;.;.;D;.;.;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0010	D;D;.;.;.;.;.;.;.;D;.;.;D;D;.;.;D;.;.;D
Sift4G	Uncertain	0.0030	D;D;T;T;T;T;T;T;D;D;D;D;D;D;D;D;D;D;D;T
Polyphen		1.0	D;.;.;.;.;.;.;.;.;D;.;D;P;D;.;.;D;.;.;.
Vest4		0.94
MutPred		0.96		Loss of disorder (P = 0.1333);Loss of disorder (P = 0.1333);.;.;.;.;.;.;.;Loss of disorder (P = 0.1333);.;Loss of disorder (P = 0.1333);Loss of disorder (P = 0.1333);Loss of disorder (P = 0.1333);.;.;Loss of disorder (P = 0.1333);.;.;.;
MVP		1.0
MPC		0.36
ClinPred		1.0	D
GERP RS		3.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.98
gMVP		0.79
Mutation Taster		=1/99	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs587781433; hg19: chr17-7577515; COSMIC: COSV53050299;