NM_006772.3:c.886T>G

Variant names:

• chr6-33437791-T-G
• rs1554121193
• NM_006772.3:c.886T>G

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_006772.3(SYNGAP1):​c.886T>G​(p.Ser296Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.06
• Publications: 0 publications found

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]

SYNGAP1-AS1 (HGNC:53831): (SYNGAP1 antisense RNA 1)

ACMG classification

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

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 8 uncertain in NM_006772.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.27788103).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SYNGAP1	NM_006772.3	c.886T>G	p.Ser296Ala	missense_variant	Exon 8 of 19	ENST00000646630.1	NP_006763.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.886T>G	p.Ser296Ala	missense_variant	Exon 8 of 19		NM_006772.3	ENSP00000496007.1
SYNGAP1	ENST00000644458.1	c.886T>G	p.Ser296Ala	missense_variant	Exon 8 of 19			ENSP00000495541.1
SYNGAP1	ENST00000449372.7	c.886T>G	p.Ser296Ala	missense_variant	Exon 8 of 18	5		ENSP00000416519.4
SYNGAP1	ENST00000418600.7	c.886T>G	p.Ser296Ala	missense_variant	Exon 8 of 19	5		ENSP00000403636.3
SYNGAP1	ENST00000645250.1	c.709T>G	p.Ser237Ala	missense_variant	Exon 6 of 17			ENSP00000494861.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Uncertain:1

Jul 27, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (ExAC no frequency). 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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with SYNGAP1-related disease. This sequence change replaces serine with alanine at codon 296 of the SYNGAP1 protein (p.Ser296Ala). The serine residue is highly conserved and there is a moderate physicochemical difference between serine and alanine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.25
BayesDel_addAF	Benign	-0.016	T
BayesDel_noAF	Benign	-0.26
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Benign	0.19	T;T;.;.;.;.;.;.
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Benign	0.74	.;T;T;T;T;T;T;T
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.28	T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.59	T
MutationAssessor	Benign	1.5	L;L;.;.;L;L;.;.
PhyloP100		2.1
PrimateAI	Uncertain	0.73	T
PROVEAN	Benign	-1.8	.;.;.;N;.;N;N;.
REVEL	Benign	0.21
Sift	Benign	0.23	.;.;.;T;.;T;T;.
Sift4G	Benign	0.15	.;T;.;T;T;T;T;.
Polyphen		0.99	D;D;.;B;D;D;.;.
Vest4		0.22, 0.47, 0.32, 0.29
MutPred		0.28		Loss of phosphorylation at S296 (P = 0.0305);Loss of phosphorylation at S296 (P = 0.0305);Loss of phosphorylation at S296 (P = 0.0305);Loss of phosphorylation at S296 (P = 0.0305);Loss of phosphorylation at S296 (P = 0.0305);Loss of phosphorylation at S296 (P = 0.0305);.;.;
MVP		0.27
MPC		2.1
ClinPred		0.78	D
GERP RS		4.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.11
gMVP		0.67
Mutation Taster		=72/28	polymorphism

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: rs1554121193; hg19: chr6-33405568;