rs1554120589

chr6-33432781-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 5P and 1B. PM2 PP2 PP5_Moderate BP4

The NM_006772.3(SYNGAP1):c.484C>T(p.Arg162Cys) 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. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R162G) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 0.669

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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, SYNGAP1
• PP5: Variant 6-33432781-C-T is Pathogenic according to our data. Variant chr6-33432781-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 438306.Status of the report is criteria_provided_single_submitter, 1 stars.
• BP4: Computational evidence support a benign effect (MetaRNN=0.24974942).. Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SYNGAP1	NM_006772.3	c.484C>T	p.Arg162Cys	missense_variant	5/19	ENST00000646630.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.484C>T	p.Arg162Cys	missense_variant	5/19		NM_006772.3	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 37

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals

Dec 09, 2016

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Feb 01, 2023

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 31395010, 35599849) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Uncertain	0.014	T
BayesDel_noAF	Benign	-0.22
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Benign	0.18	T;T;.;.;.;.;.;.
Eigen	Benign	0.094
Eigen_PC	Benign	0.14
FATHMM_MKL	Benign	0.75	D
M_CAP	Benign	0.021	T
MetaRNN	Benign	0.25	T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.69	N;N;.;.;N;N;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.90	D
Polyphen		0.99	D;D;.;D;D;.;.;.
Vest4		0.41, 0.34, 0.45, 0.53
MutPred		0.34		Loss of MoRF binding (P = 0.0064);Loss of MoRF binding (P = 0.0064);Loss of MoRF binding (P = 0.0064);Loss of MoRF binding (P = 0.0064);Loss of MoRF binding (P = 0.0064);Loss of MoRF binding (P = 0.0064);.;.;
MVP		0.66
MPC		2.4
ClinPred		0.76	D
GERP RS		3.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.13
gMVP		0.88

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1554120589; hg19: chr6-33400558;