6-33440787-C-G

Variant names:

• chr6-33440787-C-G
• rs121918316
• NM_006772.3:c.1735C>G

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.1735C>G​(p.Arg579Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,224 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R579Q) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.204
• Publications: 12 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 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 8 uncertain in NM_006772.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.845

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SYNGAP1	NM_006772.3	MANE Select	c.1735C>G	p.Arg579Gly	missense	Exon 11 of 19	NP_006763.2	A0A1U9X8L0
	SYNGAP1	NM_001130066.2		c.1735C>G	p.Arg579Gly	missense	Exon 11 of 18	NP_001123538.1	B7ZCA0
	SYNGAP1-AS1	NR_174954.1		n.330-3306G>C		intron	N/A

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SYNGAP1	ENST00000646630.1	MANE Select	c.1735C>G	p.Arg579Gly	missense	Exon 11 of 19	ENSP00000496007.1	Q96PV0-1
	SYNGAP1	ENST00000644458.1		c.1735C>G	p.Arg579Gly	missense	Exon 11 of 19	ENSP00000495541.1	A0A2R8Y6T2
	SYNGAP1	ENST00000449372.7	TSL:5	c.1735C>G	p.Arg579Gly	missense	Exon 11 of 18	ENSP00000416519.4	B7ZCA0

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152224 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 39

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152224 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 74364

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41444

American (AMR) AF: 0.00 AC: 0 AN: 15282

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68044

Other (OTH) AF: 0.00 AC: 0 AN: 2094

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.78	D
Eigen	Uncertain	0.67
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Uncertain	0.97	D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.84	D
MetaSVM	Uncertain	0.38	D
MutationAssessor	Uncertain	2.6	M
PhyloP100		0.20
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-5.8	D
REVEL	Pathogenic	0.68
Sift	Uncertain	0.022	D
Sift4G	Uncertain	0.036	D
Polyphen		1.0	D
Vest4		0.78
MutPred		0.74		Loss of MoRF binding (P = 0.0578)
MVP		0.86
MPC		2.6
ClinPred		0.99	D
GERP RS		5.2
Varity_R		0.85
gMVP		0.84
Mutation Taster		=40/60	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

dbSNP: rs121918316; hg19: chr6-33408564;