NM_006772.3:c.881C>T

Variant names:

• chr6-33437786-C-T
• NM_006772.3:c.881C>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_006772.3(SYNGAP1):​c.881C>T​(p.Thr294Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. T294T) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.91
• 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: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 9 uncertain in NM_006772.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.868

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006772.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SYNGAP1	NM_006772.3	MANE Select	c.881C>T	p.Thr294Ile	missense	Exon 8 of 19	NP_006763.2
	SYNGAP1	NM_001130066.2		c.881C>T	p.Thr294Ile	missense	Exon 8 of 18	NP_001123538.1
	SYNGAP1-AS1	NR_174954.1		n.330-305G>A		intron	N/A

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SYNGAP1	ENST00000646630.1	MANE Select	c.881C>T	p.Thr294Ile	missense	Exon 8 of 19	ENSP00000496007.1
	SYNGAP1	ENST00000644458.1		c.881C>T	p.Thr294Ile	missense	Exon 8 of 19	ENSP00000495541.1
	SYNGAP1	ENST00000449372.7	TSL:5	c.881C>T	p.Thr294Ile	missense	Exon 8 of 18	ENSP00000416519.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Uncertain	0.27	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Uncertain	0.43	D
MutationAssessor	Pathogenic	3.3	M
PhyloP100		7.9
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.48
MutPred		0.47		Loss of disorder (P = 0.0344)
MVP		0.83
MPC		2.4
ClinPred		1.0	D
GERP RS		4.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.18
gMVP		0.97
Mutation Taster		=17/83	disease causing

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

hg19: chr6-33405563;