rs199605762
Variant summary
Our verdict is Likely benign. The variant received -4 ACMG points: 1P and 5B. PP2BP4BS2
The NM_006218.4(PIK3CA):c.954G>A(p.Met318Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000558 in 1,613,662 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. M318V) has been classified as Uncertain significance.
Frequency
Consequence
NM_006218.4 missense
Scores
Clinical Significance
Conservation
Publications
- overgrowth syndrome and/or cerebral malformations due to abnormalities in MTOR pathway genesInheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
- megalencephaly-capillary malformation-polymicrogyria syndromeInheritance: AD Classification: STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
- vascular malformationInheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
- Cowden diseaseInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- Cowden syndrome 5Inheritance: AD Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
- familial ovarian cancerInheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
- hereditary breast carcinomaInheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
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ACMG classification
Our verdict: Likely_benign. The variant received -4 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.0000131 AC: 2AN: 152144Hom.: 0 Cov.: 32 show subpopulations
GnomAD2 exomes AF: 0.00000401 AC: 1AN: 249400 AF XY: 0.00 show subpopulations
GnomAD4 exome AF: 0.00000479 AC: 7AN: 1461518Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3AN XY: 727060 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.0000131 AC: 2AN: 152144Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0AN XY: 74326 show subpopulations
ClinVar
Submissions by phenotype
Inborn genetic diseases Uncertain:1
The p.M318I variant (also known as c.954G>A), located in coding exon 4 of the PIK3CA gene, results from a G to A substitution at nucleotide position 954. The methionine at codon 318 is replaced by isoleucine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
not provided Uncertain:1
In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -
Cowden syndrome 5 Uncertain:1
This variant is present in the healthy population databases with low frequency (gnomAD v4.1.0 genomes and exomes). In silico predictions for this missense variant are uncertain. The variant might have a mild splicing impact, but there is no functional data available to support this prediction. The variant was tested in parents of our patient using Sanger sequencing, and it was discovered that it was inherited from his father, phenotypically normal. Therefore, the variant was classified of uncertain significance, with criteria for benignity (class 3), according to ACMG and ClinGen criteria. -
Cowden syndrome Uncertain:1
This sequence change replaces methionine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 318 of the PIK3CA protein (p.Met318Ile). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with PIK3CA-related conditions. ClinVar contains an entry for this variant (Variation ID: 577897). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on PIK3CA protein function. 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. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at