chr3-179219590-A-G

Position:

• chr3-179219590-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_006218.4(PIK3CA):​c.1766A>G​(p.Asp589Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. D589D) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: PIK3CA NM_006218.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.95

Genes affected

PIK3CA (HGNC:8975): (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) Phosphatidylinositol 3-kinase is composed of an 85 kDa regulatory subunit and a 110 kDa catalytic subunit. The protein encoded by this gene represents the catalytic subunit, which uses ATP to phosphorylate PtdIns, PtdIns4P and PtdIns(4,5)P2. This gene has been found to be oncogenic and has been implicated in cervical cancers. A pseudogene of this gene has been defined on chromosome 22. [provided by RefSeq, Apr 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a domain PIK helical (size 177) in uniprot entity PK3CA_HUMAN there are 28 pathogenic changes around while only 0 benign (100%) in NM_006218.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), PIK3CA. . Gene score misZ 5.5986 (greater than the threshold 3.09). Trascript score misZ 6.1406 (greater than threshold 3.09). GenCC has associacion of gene with hereditary breast carcinoma, vascular malformation, Cowden disease, Cowden syndrome 5, CLOVES syndrome, familial ovarian cancer, megalencephaly-capillary malformation-polymicrogyria syndrome, overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
PIK3CA	NM_006218.4	c.1766A>G	p.Asp589Gly	missense_variant	12/21	ENST00000263967.4
PIK3CA	XM_006713658.5	c.1766A>G	p.Asp589Gly	missense_variant	12/21

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
PIK3CA	ENST00000263967.4	c.1766A>G	p.Asp589Gly	missense_variant	12/21	2	NM_006218.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 20

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cowden syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 12, 2016

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on mRNA splicing suggest that this variant may alter mRNA splicing, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a PIK3CA-related disease. This sequence change replaces aspartic acid with glycine at codon 589 of the PIK3CA protein (p.Asp589Gly). The aspartic acid residue is moderately conserved and there is a moderate physicochemical difference between aspartic acid and glycine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.030
CADD	Uncertain	23
DANN	Benign	0.97
DEOGEN2	Uncertain	0.74	D;.
Eigen	Benign	0.13
Eigen_PC	Uncertain	0.33
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D
M_CAP	Benign	0.025	T
MetaRNN	Uncertain	0.53	D;D
MetaSVM	Benign	-0.90	T
MutationAssessor	Benign	1.2	L;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.73	T
PROVEAN	Benign	-1.5	N;.
REVEL	Benign	0.25
Sift	Benign	0.38	T;.
Sift4G	Benign	0.38	T;.
Polyphen		0.10	B;.
Vest4		0.58
MutPred		0.54		Loss of ubiquitination at K594 (P = 0.0768);Loss of ubiquitination at K594 (P = 0.0768);
MVP		0.84
MPC		1.9
ClinPred		0.70	D
GERP RS		6.0
Varity_R		0.45
gMVP		0.47

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

Publications

LitVar

Other links and lift over

dbSNP: rs1060500028; hg19: chr3-178937378;