chr6-33446786-G-C

Variant names:

• chr6-33446786-G-C
• rs1554122763
• NM_006772.3:c.3794G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2 PP2 PP3_Strong PP5_Moderate

The NM_006772.3(SYNGAP1):​c.3794G>C​(p.Arg1265Thr) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 10.0

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_pathogenic. Variant got 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the SYNGAP1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 56 curated pathogenic missense variants (we use a threshold of 10). The gene has 112 curated benign missense variants. Gene score misZ: 5.6047 (above the threshold of 3.09). Trascript score misZ: 7.6762 (above the threshold of 3.09). GenCC associations: The gene is linked to autosomal dominant non-syndromic intellectual disability, complex neurodevelopmental disorder, intellectual disability, autosomal dominant 5, SYNGAP1-related developmental and epileptic encephalopathy, myoclonic-astatic epilepsy.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.
• PP5: Variant 6-33446786-G-C is Pathogenic according to our data. Variant chr6-33446786-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 522047.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SYNGAP1	NM_006772.3	c.3794G>C	p.Arg1265Thr	missense_variant, splice_region_variant	Exon 17 of 19	ENST00000646630.1	NP_006763.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.3794G>C	p.Arg1265Thr	missense_variant, splice_region_variant	Exon 17 of 19		NM_006772.3	ENSP00000496007.1
SYNGAP1	ENST00000644458.1	c.3794G>C	p.Arg1265Thr	missense_variant, splice_region_variant	Exon 17 of 19			ENSP00000495541.1
SYNGAP1	ENST00000449372.7	c.3746G>C	p.Arg1249Thr	missense_variant, splice_region_variant	Exon 16 of 18	5		ENSP00000416519.4
SYNGAP1	ENST00000418600.7	c.3794G>C	p.Ser1265Thr	missense_variant, splice_region_variant	Exon 17 of 19	5		ENSP00000403636.3
SYNGAP1	ENST00000645250.1	c.3617G>C	p.Arg1206Thr	missense_variant, splice_region_variant	Exon 15 of 17			ENSP00000494861.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Sep 18, 2017

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Uncertain	0.13	D
BayesDel_noAF	Uncertain	-0.060
CADD	Pathogenic	35
DANN	Uncertain	0.99
DEOGEN2	Benign	0.36	T;T;.;.;.;.;.
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.99	.;D;D;D;D;D;D
M_CAP	Uncertain	0.095	D
MetaRNN	Uncertain	0.71	D;D;D;D;D;D;D
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.4	M;M;.;.;M;.;.
PrimateAI	Pathogenic	0.80	D
PROVEAN	Pathogenic	-4.8	.;.;.;D;.;D;.
REVEL	Uncertain	0.53
Sift	Pathogenic	0.0	.;.;.;D;.;D;.
Sift4G	Pathogenic	0.0010	.;D;.;D;D;D;.
Polyphen		1.0	D;D;.;.;D;.;.
Vest4		0.84, 0.93, 0.91
MutPred		0.45		Loss of MoRF binding (P = 0.0095);Loss of MoRF binding (P = 0.0095);Loss of MoRF binding (P = 0.0095);.;Loss of MoRF binding (P = 0.0095);.;.;
MVP		0.65
ClinPred		1.0	D
GERP RS		5.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8
Varity_R		0.40
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.22		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.22		Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554122763; hg19: chr6-33414563;