chr6-33432806-G-A

Position:

• chr6-33432806-G-A

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_006772.3(SYNGAP1):​c.509G>A​(p.Arg170Gln) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. 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. R170L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SYNGAP1 NM_006772.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.27

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]

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a domain PH (size 101) in uniprot entity SYGP1_HUMAN there are 5 pathogenic changes around while only 2 benign (71%) in NM_006772.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr6-33432806-G-T is described in Lovd as [Likely_pathogenic].
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SYNGAP1. . Gene score misZ 5.6047 (greater than the threshold 3.09). Trascript score misZ 7.6762 (greater than threshold 3.09). GenCC has associacion of gene with 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, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 6-33432806-G-A is Pathogenic according to our data. Variant chr6-33432806-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 375528.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-33432806-G-A is described in Lovd as [Likely_pathogenic]. Variant chr6-33432806-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SYNGAP1	NM_006772.3	c.509G>A	p.Arg170Gln	missense_variant, splice_region_variant	5/19	ENST00000646630.1	NP_006763.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.509G>A	p.Arg170Gln	missense_variant, splice_region_variant	5/19		NM_006772.3	ENSP00000496007	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 38

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics Munich, Klinikum Rechts Der Isar, TU München	May 22, 2019	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Neurogenetics Laboratory - MEYER, AOU Meyer	Nov 16, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	-	The variant is not observed in the gnomAD v2.1.1 dataset. In silico tools predict the variant to alter splicing and produce an abnormal transcript (SpliceAI: 0.77). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000375528 / PMID: 26079862). The variant has been previously reported as de novo in a similarly affected individual (PMID: 25533962). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Benign	-0.040	T
BayesDel_noAF	Benign	-0.29
CADD	Pathogenic	36
DANN	Pathogenic	1.0
DEOGEN2	Benign	0.31	T;T;.;.;.;.;.;.
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.87	.;D;D;D;D;D;D;D
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.32	T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.3	M;M;.;.;M;M;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.75	T
PROVEAN	Benign	-2.3	.;.;.;N;.;N;N;.
REVEL	Benign	0.22
Sift	Uncertain	0.0030	.;.;.;D;.;D;D;.
Sift4G	Uncertain	0.0070	.;D;.;D;D;D;D;.
Polyphen		0.95	P;P;.;D;D;.;.;.
Vest4		0.57, 0.41, 0.55, 0.53
MutPred		0.29		Loss of methylation at R170 (P = 0.0528);Loss of methylation at R170 (P = 0.0528);Loss of methylation at R170 (P = 0.0528);Loss of methylation at R170 (P = 0.0528);Loss of methylation at R170 (P = 0.0528);Loss of methylation at R170 (P = 0.0528);.;.;
MVP		0.47
MPC		1.9
ClinPred		0.94	D
GERP RS		4.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.14
gMVP		0.82

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.77		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.53		Position offset: 34
DS_DL_spliceai		0.77		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: rs1057519546; hg19: chr6-33400583;