6-33438426-T-C

Variant names:

• chr6-33438426-T-C
• NM_006772.3:c.1394T>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.1394T>C​(p.Leu465Pro) 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SYNGAP1 NM_006772.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.02

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]

MIR5004 (HGNC:43532): (microRNA 5004) microRNAs (miRNAs) are short (20-24 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. miRNAs are transcribed by RNA polymerase II as part of capped and polyadenylated primary transcripts (pri-miRNAs) that can be either protein-coding or non-coding. The primary transcript is cleaved by the Drosha ribonuclease III enzyme to produce an approximately 70-nt stem-loop precursor miRNA (pre-miRNA), which is further cleaved by the cytoplasmic Dicer ribonuclease to generate the mature miRNA and antisense miRNA star (miRNA*) products. The mature miRNA is incorporated into a RNA-induced silencing complex (RISC), which recognizes target mRNAs through imperfect base pairing with the miRNA and most commonly results in translational inhibition or destabilization of the target mRNA. The RefSeq represents the predicted microRNA stem-loop. [provided by RefSeq, Sep 2009]

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: MetaRNN computational evidence supports a deleterious effect, 0.978
• PP5: Variant 6-33438426-T-C is Pathogenic according to our data. Variant chr6-33438426-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1067821.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.1394T>C	p.Leu465Pro	missense_variant	Exon 9 of 19	ENST00000646630.1	NP_006763.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SYNGAP1	ENST00000646630.1	c.1394T>C	p.Leu465Pro	missense_variant	Exon 9 of 19		NM_006772.3	ENSP00000496007.1
SYNGAP1	ENST00000644458.1	c.1394T>C	p.Leu465Pro	missense_variant	Exon 9 of 19			ENSP00000495541.1
SYNGAP1	ENST00000449372.7	c.1394T>C	p.Leu465Pro	missense_variant	Exon 9 of 18	5		ENSP00000416519.4
SYNGAP1	ENST00000418600.7	c.1394T>C	p.Leu465Pro	missense_variant	Exon 9 of 19	5		ENSP00000403636.3
SYNGAP1	ENST00000645250.1	c.1217T>C	p.Leu406Pro	missense_variant	Exon 7 of 17			ENSP00000494861.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability, autosomal dominant 5 Pathogenic:1

Sep 10, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has been observed in individual(s) with clinical features of SYNGAP1-related conditions (Invitae). In at least one individual the variant was observed to be de novo. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with proline at codon 465 of the SYNGAP1 protein (p.Leu465Pro). The leucine residue is highly conserved and there is a moderate physicochemical difference between leucine and proline. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	D;D;.;.;.;.;.;.
Eigen	Pathogenic	0.84
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	.;D;D;D;D;D;D;D
M_CAP	Uncertain	0.14	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D
MetaSVM	Benign	-0.58	T
MutationAssessor	Pathogenic	3.5	M;M;.;.;M;M;.;.
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-6.8	.;.;.;D;.;D;D;.
REVEL	Pathogenic	0.78
Sift	Pathogenic	0.0	.;.;.;D;.;D;D;.
Sift4G	Pathogenic	0.0	.;D;.;D;D;D;D;.
Polyphen		1.0	D;D;.;D;D;D;.;.
Vest4		0.95, 0.95, 0.96, 0.95
MutPred		0.93		Gain of disorder (P = 0.0158);Gain of disorder (P = 0.0158);Gain of disorder (P = 0.0158);Gain of disorder (P = 0.0158);Gain of disorder (P = 0.0158);Gain of disorder (P = 0.0158);.;.;
MVP		0.85
MPC		2.8
ClinPred		1.0	D
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.80
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr6-33406203;