rs768878991

Positions:

• chr6-33443148-G-A
• chr6-33443148-G-T

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 3P and 7B. PM2 PP2 BP4_Moderate BP6 BS2

The NM_006772.3(SYNGAP1):​c.2596G>A​(p.Val866Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,732 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V866L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:1
• Conservation: PhyloP100: 1.96

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

Verdict is Likely_benign. Variant got -4 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=0.12901923).
• BP6: Variant 6-33443148-G-A is Benign according to our data. Variant chr6-33443148-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 536995.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=2, Benign=1}.
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SYNGAP1	NM_006772.3	c.2596G>A	p.Val866Ile	missense_variant	15/19	ENST00000646630.1
SYNGAP1-AS1	NR_174954.1	n.329+3458C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.2596G>A	p.Val866Ile	missense_variant	15/19		NM_006772.3	P1
SYNGAP1-AS1	ENST00000630418.1	n.377+3458C>T		intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000400 AC: 1 AN: 250114 Hom.: 0 AF XY: 0.00000739 AC XY: 1 AN XY: 135346

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: 0.0000465

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461732 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727176

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: 0.0000188

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000283 Hom.: 0

Bravo AF: 0.0000113

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	New York Genome Center	Nov 12, 2020	- -
Benign, criteria provided, single submitter	clinical testing	Invitae	Mar 14, 2023	- -

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 01, 2016

The p.V866I variant (also known as c.2596G>A), located in coding exon 15 of the SYNGAP1 gene, results from a G to A substitution at nucleotide position 2596. The valine at codon 866 is replaced by isoleucine, an amino acid with highly similar properties. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6503 samples (13006 alleles) with coverage at this position. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	-0.20	T
BayesDel_noAF	Benign	-0.52
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Benign	0.050	T;T;.;.;.;.;.;.
Eigen	Benign	-0.032
Eigen_PC	Benign	-0.066
FATHMM_MKL	Benign	0.67	D
M_CAP	Benign	0.024	T
MetaRNN	Benign	0.13	T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.2	L;L;.;.;L;L;.;.
MutationTaster	Benign	0.99	D;D;D;D
PrimateAI	Uncertain	0.59	T
Polyphen		0.96	D;D;.;.;P;P;.;.
Vest4		0.13, 0.12, 0.21, 0.14
MutPred		0.14		Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);.;Loss of loop (P = 0.1242);Loss of loop (P = 0.1242);.;.;
MVP		0.30
MPC		1.6
ClinPred		0.41	T
GERP RS		3.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.041
gMVP		0.38

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: rs768878991; hg19: chr6-33410925;