chr3-179198937-C-T

Variant names:

• chr3-179198937-C-T
• rs749415085
• NM_006218.4:c.112C>T

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_006218.4(PIK3CA):​c.112C>T​(p.Arg38Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. R38H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: PIK3CA NM_006218.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 7.52
• Publications: 79 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: Ambry Genetics, Labcorp Genetics (formerly Invitae), 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)
• familial ovarian cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
• hereditary breast carcinoma

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a domain PI3K-ABD (size 89) in uniprot entity PK3CA_HUMAN there are 9 pathogenic changes around while only 2 benign (82%) in NM_006218.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-179198938-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 376492.Status of the report is criteria_provided_single_submitter, 1 stars.
• 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.889

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PIK3CA	NM_006218.4	MANE Select	c.112C>T	p.Arg38Cys	missense	Exon 2 of 21	NP_006209.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	PIK3CA	ENST00000263967.4	TSL:2 MANE Select	c.112C>T	p.Arg38Cys	missense	Exon 2 of 21	ENSP00000263967.3
	PIK3CA	ENST00000643187.1		c.112C>T	p.Arg38Cys	missense	Exon 2 of 22	ENSP00000493507.1
	PIK3CA	ENST00000468036.1	TSL:3	c.112C>T	p.Arg38Cys	missense	Exon 2 of 2	ENSP00000417479.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00 AC: 0 AN: 248624 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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1458900 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 725880

African (AFR) AF: 0.00 AC: 0 AN: 33376

American (AMR) AF: 0.00 AC: 0 AN: 44574

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26074

East Asian (EAS) AF: 0.00 AC: 0 AN: 39658

South Asian (SAS) AF: 0.00 AC: 0 AN: 85976

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53404

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109766

Other (OTH) AF: 0.00 AC: 0 AN: 60310

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000828 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

May 24, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously reported as a pathogenic or benign germline variant to our knowledge; This variant is associated with the following publications: (PMID: 29438965, 26619011, 31565188, 33148674, 32269842, 34693559, 35070505, 35626111)

Cowden syndrome Uncertain:1

May 07, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine with cysteine at codon 38 of the PIK3CA protein (p.Arg38Cys). The arginine residue is highly conserved and there is a large physicochemical difference between arginine and cysteine. This variant is present in population databases (rs749415085, ExAC 0.002%). This variant has not been reported in the literature in individuals with PIK3CA-related conditions. ClinVar contains an entry for this variant (Variation ID: 376493). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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.

Colorectal cancer Other:1

Jul 11, 2016

Genome Sciences Centre, British Columbia Cancer Agency

Significance:

Review Status: no assertion criteria provided

Collection Method: research

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.86	D
Eigen	Uncertain	0.68
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Uncertain	0.17	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Uncertain	-0.035	T
MutationAssessor	Benign	1.9	L
PhyloP100		7.5
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-5.2	D
REVEL	Pathogenic	0.74
Sift	Benign	0.072	T
Sift4G	Benign	0.061	T
Polyphen		1.0	D
Vest4		0.80
MutPred		0.74		Gain of sheet (P = 0.0827)
MVP		0.89
MPC		2.2
ClinPred		1.0	D
GERP RS		5.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.85
gMVP		0.83
Mutation Taster		=72/28	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: rs749415085; hg19: chr3-178916725; COSMIC: COSV55874617; COSMIC: COSV55874617;