5-112815495-G-T

Position:

• chr5-112815495-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000038.6(APC):​c.835G>T​(p.Gly279Cys) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. 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. G279V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 missense, splice_region
• Scores: Splicing: ADA: 0.9830
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 2.18

Genes affected

APC (HGNC:583): (APC regulator of WNT signaling pathway) This gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. It is also involved in other processes including cell migration and adhesion, transcriptional activation, and apoptosis. Defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Mutations in the APC gene have been found to occur in most colorectal cancers, where disease-associated mutations tend to be clustered in a small region designated the mutation cluster region (MCR) and result in a truncated protein product. [provided by RefSeq, Jun 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 17 uncertain in NM_000038.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.835G>T	p.Gly279Cys	missense_variant, splice_region_variant	9/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.835G>T	p.Gly279Cys	missense_variant, splice_region_variant	9/16	5	NM_000038.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Quest Diagnostics Nichols Institute San Juan Capistrano	Dec 18, 2017	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Nov 07, 2019	Not observed in large population cohorts (Lek 2016); Observed in individuals with a Lynch Syndrome-associated cancer and/or polyps (Yurgelun 2015); This variant is associated with the following publications: (PMID: 25980754) -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Oct 24, 2023

Variant summary: APC c.835G>T (p.Gly279Cys) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. Several computational tools predict a significant impact on normal splicing: One predict the variant abolishes a 3' acceptor site. Two predict the variant weakens a 3' acceptor site. One predict the variant no significant impact on splicing. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 250998 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.835G>T has been reported in the literature in at least one individual affected with Lynch Syndrome without strong evidence of causality (Yurgelun_2015). This report does not provide unequivocal conclusions about association of the variant with Familial Adenomatous Polyposis. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Four submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Familial adenomatous polyposis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 09, 2024

This sequence change replaces glycine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 279 of the APC protein (p.Gly279Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Lynch syndrome (PMID: 25980754). ClinVar contains an entry for this variant (Variation ID: 482275). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 09, 2024

The p.G279C variant (also known as c.835G>T) is located in coding exon 8 of the APC gene. The glycine at codon 279 is replaced by cysteine, an amino acid with highly dissimilar properties. This change occurs in the first base pair of coding exon 8. This amino acid position is not well conserved in available vertebrate species. In addition, in silico predictors for this gene do not accurately predict pathogenicity. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.097
BayesDel_addAF	Uncertain	0.15	D
BayesDel_noAF	Uncertain	-0.030
CADD	Benign	22
DANN	Uncertain	1.0
Eigen	Uncertain	0.20
Eigen_PC	Benign	0.20
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.85	T;.;T;T
M_CAP	Uncertain	0.21	D
MetaRNN	Benign	0.30	T;T;T;T
MetaSVM	Uncertain	0.21	D
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-2.0	N;N;N;N
REVEL	Uncertain	0.52
Sift	Uncertain	0.0090	D;D;D;D
Sift4G	Uncertain	0.052	T;T;T;T
Polyphen		0.88	.;P;P;.
Vest4		0.70, 0.68
MutPred		0.23		.;Gain of loop (P = 0.0051);Gain of loop (P = 0.0051);Gain of loop (P = 0.0051);
MVP		0.90
ClinPred		0.86	D
GERP RS		3.3
Varity_R		0.17
gMVP		0.43

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.98
dbscSNV1_RF	Pathogenic	0.79
SpliceAI score (max)		0.35		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.35		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554079129; hg19: chr5-112151192;