6-33420307-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_006772.3(SYNGAP1):c.43G>A(p.Ala15Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000288 in 1,389,654 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict 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. A15V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 28)
  • Exomes 𝑓: 0.0000029 (0 hom.)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.48

Genes affected

SYNGAP1 (HGNC:11497): (synaptic Ras GTPase activating protein 1) This gene encodes a Ras GTPase activating protein that is a member of the N-methyl-D-aspartate receptor complex. The N-terminal domain of the protein contains a Ras-GAP domain, a pleckstrin homology domain, and a C2 domain that may be involved in binding of calcium and phospholipids. The C-terminal domain consists of a ten histidine repeat region, serine and tyrosine phosphorylation sites, and a T/SXV motif required for postsynaptic scaffold protein interaction. The encoded protein negatively regulates Ras, Rap and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor trafficking to the postsynaptic membrane to regulate synaptic plasticity and neuronal homeostasis. Allelic variants of this gene are associated with intellectual disability and autism spectrum disorder. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, SYNGAP1
• BP4: Computational evidence support a benign effect (MetaRNN=0.1735861).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SYNGAP1	NM_006772.3	c.43G>A	p.Ala15Thr	missense_variant	1/19	ENST00000646630.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.43G>A	p.Ala15Thr	missense_variant	1/19		NM_006772.3	P1

Frequencies

GnomAD3 genomes Cov.: 28

GnomAD3 exomes AF: 0.0000137 AC: 2 AN: 146214 Hom.: 0 AF XY: 0.0000126 AC XY: 1 AN XY: 79082

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000376

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000288 AC: 4 AN: 1389654 Hom.: 0 Cov.: 31 AF XY: 0.00000146 AC XY: 1 AN XY: 685184

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000372

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 28

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jun 23, 2022

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SYNGAP1 protein function. This variant has not been reported in the literature in individuals affected with SYNGAP1-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 15 of the SYNGAP1 protein (p.Ala15Thr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.50
Cadd	Benign	22
Dann	Uncertain	0.99
DEOGEN2	Benign	0.047	T;T;.;.;.;.
Eigen	Benign	-0.21
Eigen_PC	Benign	-0.13
FATHMM_MKL	Uncertain	0.88	D
M_CAP	Benign	0.080	D
MetaRNN	Benign	0.17	T;T;T;T;T;T
MetaSVM	Benign	-0.99	T
MutationAssessor	Benign	0.0	N;N;.;.;N;N
MutationTaster	Benign	0.99	N;N;N
PrimateAI	Pathogenic	0.89	D
Polyphen		0.60	P;P;.;.;.;.
Vest4		0.28, 0.29, 0.21
MutPred		0.19		Gain of glycosylation at A15 (P = 0.0044);Gain of glycosylation at A15 (P = 0.0044);Gain of glycosylation at A15 (P = 0.0044);Gain of glycosylation at A15 (P = 0.0044);Gain of glycosylation at A15 (P = 0.0044);Gain of glycosylation at A15 (P = 0.0044);
MVP		0.068
MPC		1.1
ClinPred		0.22	T
GERP RS		3.7
Varity_R		0.10
gMVP		0.32

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: rs1299171563; hg19: chr6-33388084;