6-33438895-T-C

Variant names:

• chr6-33438895-T-C
• rs1554121453
• NM_006772.3:c.1652T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_006772.3(SYNGAP1):​c.1652T>C​(p.Leu551Pro) 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. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L551M) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.01
• Publications: 1 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 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.971
• PP5: Variant 6-33438895-T-C is Pathogenic according to our data. Variant chr6-33438895-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 547942.Status of the report is criteria_provided_single_submitter, 1 stars.

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.1652T>C	p.Leu551Pro	missense	Exon 10 of 19	NP_006763.2
	SYNGAP1	NM_001130066.2		c.1652T>C	p.Leu551Pro	missense	Exon 10 of 18	NP_001123538.1
	SYNGAP1-AS1	NR_174954.1		n.330-1414A>G		intron	N/A

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SYNGAP1	ENST00000646630.1	MANE Select	c.1652T>C	p.Leu551Pro	missense	Exon 10 of 19	ENSP00000496007.1
	SYNGAP1	ENST00000644458.1		c.1652T>C	p.Leu551Pro	missense	Exon 10 of 19	ENSP00000495541.1
	SYNGAP1	ENST00000449372.7	TSL:5	c.1652T>C	p.Leu551Pro	missense	Exon 10 of 18	ENSP00000416519.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions as Germline

Significance: Likely pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Intellectual disability, autosomal dominant 5 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D
Eigen	Pathogenic	0.80
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.94	D
M_CAP	Pathogenic	0.54	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Uncertain	0.48	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		8.0
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.90
MutPred		0.88		Gain of catalytic residue at L551 (P = 0.0203)
MVP		0.99
MPC		2.8
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.91
gMVP		0.99
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1554121453; hg19: chr6-33406672;