2-170818629-C-T

Position:

• chr2-170818629-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP2 BP4

The NM_000817.3(GAD1):​c.38C>T​(p.Ser13Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,884 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. S13S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GAD1 NM_000817.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.62

Genes affected

GAD1 (HGNC:4092): (glutamate decarboxylase 1) This gene encodes one of several forms of glutamic acid decarboxylase, identified as a major autoantigen in insulin-dependent diabetes. The enzyme encoded is responsible for catalyzing the production of gamma-aminobutyric acid from L-glutamic acid. A pathogenic role for this enzyme has been identified in the human pancreas since it has been identified as an autoantigen and an autoreactive T cell target in insulin-dependent diabetes. This gene may also play a role in the stiff man syndrome. Deficiency in this enzyme has been shown to lead to pyridoxine dependency with seizures. Alternative splicing of this gene results in two products, the predominant 67-kD form and a less-frequent 25-kD form. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), GAD1. . Gene score misZ 2.3151 (greater than the threshold 3.09). Trascript score misZ 3.7409 (greater than threshold 3.09). GenCC has associacion of gene with cerebral palsy, spastic quadriplegic, 1, developmental and epileptic encephalopathy 89, early infantile epileptic encephalopathy, spastic quadriplegic cerebral palsy, neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities.
• BP4: Computational evidence support a benign effect (MetaRNN=0.27484563).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAD1	NM_000817.3	c.38C>T	p.Ser13Leu	missense_variant	2/17	ENST00000358196.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAD1	ENST00000358196.8	c.38C>T	p.Ser13Leu	missense_variant	2/17	1	NM_000817.3	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461884 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 08, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. 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: "Not Available"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals affected with GAD1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 13 of the GAD1 protein (p.Ser13Leu). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Benign	-0.090
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.26	.;.;.;T;.;.;.;.
Eigen	Uncertain	0.20
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;.;D;D
M_CAP	Benign	0.064	D
MetaRNN	Benign	0.27	T;T;T;T;T;T;T;T
MetaSVM	Uncertain	0.25	D
MutationAssessor	Benign	1.1	.;.;L;L;L;L;.;.
MutationTaster	Benign	0.87	D;D;D
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-2.5	N;D;.;N;N;N;N;N
REVEL	Benign	0.14
Sift	Uncertain	0.019	D;D;.;D;D;D;D;D
Sift4G	Uncertain	0.015	D;D;T;T;T;T;D;D
Polyphen		0.063, 0.52	.;.;.;B;P;P;.;.
Vest4		0.64, 0.56, 0.58, 0.58
MutPred		0.23		Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);Loss of glycosylation at S13 (P = 0.0057);
MVP		0.69
MPC		0.52
ClinPred		0.79	D
GERP RS		5.8
Varity_R		0.21
gMVP		0.34

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr2-171675139; COSMIC: COSV60154339; COSMIC: COSV60154339;