Genetic Variant GAD1:p.Ile228Val (chr2-170844088-A-G) – ACMG Classification: Uncertain_significance (0 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NM_000817.3(GAD1):c.682A>G(p.Ile228Val) variant causes a missense change. The variant allele was found at a frequency of 0.000000685 in 1,458,924 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign 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. I228L) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

GAD1
NM_000817.3 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 5.41

Publications

0 publications found

Variant links:

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]

GAD1 Gene-Disease associations (from GenCC):

early infantile epileptic encephalopathy
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
developmental and epileptic encephalopathy 89
Inheritance: AR Classification: STRONG, LIMITED Submitted by: G2P, Labcorp Genetics (formerly Invitae)
spastic quadriplegic cerebral palsy
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
cerebral palsy, spastic quadriplegic, 1
Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics
neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities
Inheritance: AR Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

GAD1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.17799014).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAD1	NM_000817.3 link	c.682A>G	p.Ile228Val	missense_variant	Exon 7 of 17	ENST00000358196.8	NP_000808.2	Q99259-1A0A0S2Z3V5Q8IVA8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAD1	ENST00000358196.8 link	c.682A>G	p.Ile228Val	missense_variant	Exon 7 of 17	1	NM_000817.3	ENSP00000350928.3		Q99259-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.85e-7

AC:

AN:

1458924

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726102

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33418

American (AMR)

AF:

0.00

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26104

East Asian (EAS)

AF:

0.00

AC:

AN:

39640

South Asian (SAS)

AF:

0.00

AC:

AN:

86204

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53408

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1109400

Other (OTH)

AF:

0.00

AC:

AN:

60264

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.085

BayesDel_addAF

Benign

-0.14

BayesDel_noAF

Benign

-0.44

CADD

Benign

(source)

DANN

Benign

0.89

DEOGEN2

Benign

0.19

.;T

Eigen

Benign

-0.26

Eigen_PC

Benign

0.042

FATHMM_MKL

Benign

0.68

LIST_S2

Uncertain

0.92

D;D

M_CAP

Benign

0.0055

MetaRNN

Benign

0.18

T;T

MetaSVM

Benign

-1.0

MutationAssessor

Benign

-0.58

N;N

PhyloP100

5.4

PrimateAI

Uncertain

0.74

PROVEAN

Benign

0.20

.;N

REVEL

Benign

0.14

Sift

Benign

1.0

.;T

Sift4G

Benign

1.0

T;T

Polyphen

0.0030

.;B

Vest4

0.21

MutPred

0.48

Gain of catalytic residue at I228 (P = 0.0339);Gain of catalytic residue at I228 (P = 0.0339);

MVP

0.33

MPC

0.59

ClinPred

0.94

GERP RS

6.2

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.30

gMVP

0.52

Mutation Taster

=83/17

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over