2-170852775-A-T

Position:

• chr2-170852775-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_000817.3(GAD1):​c.1246A>T​(p.Ile416Phe) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. I416V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GAD1 NM_000817.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.15

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 5 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.88

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAD1	NM_000817.3	c.1246A>T	p.Ile416Phe	missense_variant	13/17	ENST00000358196.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAD1	ENST00000358196.8	c.1246A>T	p.Ile416Phe	missense_variant	13/17	1	NM_000817.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.26
BayesDel_addAF	Pathogenic	0.16	D
BayesDel_noAF	Uncertain	-0.010
CADD	Uncertain	24
DANN	Benign	0.93
DEOGEN2	Benign	0.32	T
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.89	D
M_CAP	Benign	0.017	T
MetaRNN	Pathogenic	0.88	D
MetaSVM	Benign	-0.93	T
MutationAssessor	Benign	0.41	N
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.78	T
PROVEAN	Uncertain	-2.4	N
REVEL	Uncertain	0.30
Sift	Benign	0.44	T
Sift4G	Benign	0.75	T
Polyphen		0.99	D
Vest4		0.85
MutPred		0.75		Loss of methylation at K419 (P = 0.0823);
MVP		0.69
MPC		1.8
ClinPred		0.89	D
GERP RS		5.9
Varity_R		0.76
gMVP		0.93

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs749599647; hg19: chr2-171709285;