3-179198836-G-T

Variant names:

• chr3-179198836-G-T
• rs749956691
• NM_006218.4:c.11G>T

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP2

The NM_006218.4(PIK3CA):​c.11G>T​(p.Arg4Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000289 in 1,386,270 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R4P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000029 (0 hom.)
• Consequence: PIK3CA NM_006218.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.34
• Publications: 6 publications found

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]

PIK3CA Gene-Disease associations (from GenCC):

• overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• megalencephaly-capillary malformation-polymicrogyria syndrome

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Genomics England PanelApp
• vascular malformation

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
• Cowden disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Cowden syndrome 5

  Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• hereditary breast carcinoma

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
• familial ovarian cancer

  Inheritance: Unknown Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the PIK3CA gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 98 curated pathogenic missense variants (we use a threshold of 10). The gene has 13 curated benign missense variants. Gene score misZ: 5.5986 (above the threshold of 3.09). Trascript score misZ: 6.1406 (above the threshold of 3.09). GenCC associations: The gene is linked to megalencephaly-capillary malformation-polymicrogyria syndrome, vascular malformation, Cowden syndrome 5, overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genes, Cowden disease, hereditary breast carcinoma, familial ovarian cancer.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006218.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PIK3CA	NM_006218.4	MANE Select	c.11G>T	p.Arg4Leu	missense	Exon 2 of 21	NP_006209.2	P42336

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PIK3CA	ENST00000263967.4	TSL:2 MANE Select	c.11G>T	p.Arg4Leu	missense	Exon 2 of 21	ENSP00000263967.3	P42336
	PIK3CA	ENST00000955190.1		c.11G>T	p.Arg4Leu	missense	Exon 2 of 21	ENSP00000625249.1
	PIK3CA	ENST00000876545.1		c.11G>T	p.Arg4Leu	missense	Exon 3 of 22	ENSP00000546604.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000509 AC: 1 AN: 196622 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000104

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000289 AC: 4 AN: 1386270 Hom.: 0 Cov.: 27 AF XY: 0.00000292 AC XY: 2 AN XY: 684986

⚠️ 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: 30458

American (AMR) AF: 0.00 AC: 0 AN: 29480

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22090

East Asian (EAS) AF: 0.00 AC: 0 AN: 38830

South Asian (SAS) AF: 0.0000532 AC: 4 AN: 75182

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51120

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5440

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1076638

Other (OTH) AF: 0.00 AC: 0 AN: 57032

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0000000482131), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000828 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.71
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Benign	0.30	T
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.037	D
MetaRNN	Uncertain	0.48	T
MetaSVM	Benign	-0.80	T
MutationAssessor	Benign	0.34	N
PhyloP100		9.3
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-7.0	D
REVEL	Uncertain	0.46
Sift	Benign	0.33	T
Sift4G	Pathogenic	0.0	D
Polyphen		0.85	P
Vest4		0.69
MutPred		0.30		Loss of disorder (P = 0.085)
MVP		0.87
MPC		2.1
ClinPred		0.82	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.57
gMVP		0.64
Mutation Taster		=46/54	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs749956691; hg19: chr3-178916624;