chr6-33420292-C-T

Position:

• chr6-33420292-C-T

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.28C>T​(p.Arg10Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000144 in 1,389,302 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. R10P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 28)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.91

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 in gene, where missense usually causes diseases (based on misZ statistic), SYNGAP1. . Gene score misZ 5.6047 (greater than the threshold 3.09). Trascript score misZ 7.6762 (greater than threshold 3.09). GenCC has associacion of gene with autosomal dominant non-syndromic intellectual disability, complex neurodevelopmental disorder, intellectual disability, autosomal dominant 5, SYNGAP1-related developmental and epileptic encephalopathy, myoclonic-astatic epilepsy.
• BP4: Computational evidence support a benign effect (MetaRNN=0.18627977).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SYNGAP1	NM_006772.3	c.28C>T	p.Arg10Trp	missense_variant	1/19	ENST00000646630.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.28C>T	p.Arg10Trp	missense_variant	1/19		NM_006772.3	P1

Frequencies

GnomAD3 genomes Cov.: 28

GnomAD4 exome AF: 0.00000144 AC: 2 AN: 1389302 Hom.: 0 Cov.: 31 AF XY: 0.00000146 AC XY: 1 AN XY: 685026

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: 0.00000186

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 28

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 30, 2021

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 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.50
BayesDel_addAF	Benign	-0.11	T
BayesDel_noAF	Benign	-0.39
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Benign	0.048	T;T;.;.;.;.
Eigen	Benign	-0.28
Eigen_PC	Benign	-0.29
FATHMM_MKL	Benign	0.65	D
LIST_S2	Uncertain	0.90	.;D;D;D;D;D
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.19	T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.69	N;N;.;.;N;N
MutationTaster	Benign	0.99	N;N;N
PrimateAI	Pathogenic	0.94	D
PROVEAN	Benign	-0.31	.;.;.;N;.;N
REVEL	Benign	0.24
Sift	Pathogenic	0.0	.;.;.;D;.;D
Sift4G	Pathogenic	0.0	.;D;.;D;D;D
Polyphen		0.96	D;D;.;.;.;.
Vest4		0.27, 0.28, 0.21
MutPred		0.49		Loss of disorder (P = 0.0167);Loss of disorder (P = 0.0167);Loss of disorder (P = 0.0167);Loss of disorder (P = 0.0167);Loss of disorder (P = 0.0167);Loss of disorder (P = 0.0167);
MVP		0.068
MPC		1.1
ClinPred		0.48	T
GERP RS		2.8
Varity_R		0.21
gMVP		0.44

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1167492483; hg19: chr6-33388069;