rs774953382

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2BS1_Supporting

The NM_000817.3(GAD1):​c.1672C>G​(p.Pro558Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000651 in 1,614,040 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P558S) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)
Exomes 𝑓: 0.000068 ( 0 hom. )

Consequence

GAD1
NM_000817.3 missense

Scores

6
10
3

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 7.57

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)

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PM2
Very rare variant in population databases, with high coverage;
BS1
Variant frequency is greater than expected in population nfe. GnomAdExome4 allele frequency = 0.0000684 (100/1461822) while in subpopulation NFE AF = 0.0000863 (96/1111976). AF 95% confidence interval is 0.0000722. There are 0 homozygotes in GnomAdExome4. There are 55 alleles in the male GnomAdExome4 subpopulation. Median coverage is 31. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
GAD1NM_000817.3 linkc.1672C>G p.Pro558Ala missense_variant Exon 17 of 17 ENST00000358196.8 NP_000808.2 Q99259-1A0A0S2Z3V5Q8IVA8

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
GAD1ENST00000358196.8 linkc.1672C>G p.Pro558Ala missense_variant Exon 17 of 17 1 NM_000817.3 ENSP00000350928.3 Q99259-1

Frequencies

GnomAD3 genomes
AF:
0.0000328
AC:
5
AN:
152218
Hom.:
0
Cov.:
32
show subpopulations
Gnomad AFR
AF:
0.0000724
Gnomad AMI
AF:
0.00
Gnomad AMR
AF:
0.00
Gnomad ASJ
AF:
0.00
Gnomad EAS
AF:
0.00
Gnomad SAS
AF:
0.00
Gnomad FIN
AF:
0.00
Gnomad MID
AF:
0.00
Gnomad NFE
AF:
0.0000294
Gnomad OTH
AF:
0.00
GnomAD2 exomes
AF:
0.0000199
AC:
5
AN:
251330
AF XY:
0.0000147
show subpopulations
Gnomad AFR exome
AF:
0.00
Gnomad AMR exome
AF:
0.00
Gnomad ASJ exome
AF:
0.00
Gnomad EAS exome
AF:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.0000440
Gnomad OTH exome
AF:
0.00
GnomAD4 exome
AF:
0.0000684
AC:
100
AN:
1461822
Hom.:
0
Cov.:
31
AF XY:
0.0000756
AC XY:
55
AN XY:
727200
show subpopulations
African (AFR)
AF:
0.00
AC:
0
AN:
33480
American (AMR)
AF:
0.00
AC:
0
AN:
44714
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26134
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39700
South Asian (SAS)
AF:
0.00
AC:
0
AN:
86246
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53414
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5766
European-Non Finnish (NFE)
AF:
0.0000863
AC:
96
AN:
1111976
Other (OTH)
AF:
0.0000662
AC:
4
AN:
60392
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.459
Heterozygous variant carriers
0
6
12
18
24
30
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Exome Het
Variant carriers
0
4
8
12
16
20
<30
30-35
35-40
40-45
45-50
50-55
55-60
60-65
65-70
70-75
75-80
>80
Age
GnomAD4 genome
AF:
0.0000328
AC:
5
AN:
152218
Hom.:
0
Cov.:
32
AF XY:
0.0000269
AC XY:
2
AN XY:
74358
show subpopulations
African (AFR)
AF:
0.0000724
AC:
3
AN:
41454
American (AMR)
AF:
0.00
AC:
0
AN:
15284
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
3472
East Asian (EAS)
AF:
0.00
AC:
0
AN:
5194
South Asian (SAS)
AF:
0.00
AC:
0
AN:
4834
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
10622
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
316
European-Non Finnish (NFE)
AF:
0.0000294
AC:
2
AN:
68038
Other (OTH)
AF:
0.00
AC:
0
AN:
2092
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.505
Heterozygous variant carriers
0
1
1
2
2
3
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance
Alfa
AF:
0.000130
Hom.:
0
Bravo
AF:
0.0000302
ExAC
AF:
0.00000824
AC:
1
EpiCase
AF:
0.00
EpiControl
AF:
0.000119

ClinVar

Significance: Uncertain significance
Submissions summary: Uncertain:2
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

Inborn genetic diseases Uncertain:1
May 13, 2024
Ambry Genetics
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

The c.1672C>G (p.P558A) alteration is located in exon 17 (coding exon 16) of the GAD1 gene. This alteration results from a C to G substitution at nucleotide position 1672, causing the proline (P) at amino acid position 558 to be replaced by an alanine (A). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities Uncertain:1
Nov 10, 2022
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Uncertain significance
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces proline, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 558 of the GAD1 protein (p.Pro558Ala). This variant is present in population databases (rs774953382, gnomAD 0.004%). This variant has not been reported in the literature in individuals affected with GAD1-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GAD1 protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Uncertain
0.41
BayesDel_addAF
Uncertain
0.039
T
BayesDel_noAF
Uncertain
-0.050
CADD
Pathogenic
27
DANN
Uncertain
1.0
DEOGEN2
Pathogenic
0.85
D
Eigen
Pathogenic
0.86
Eigen_PC
Pathogenic
0.83
FATHMM_MKL
Pathogenic
0.98
D
LIST_S2
Uncertain
0.96
D
M_CAP
Benign
0.044
D
MetaRNN
Uncertain
0.64
D
MetaSVM
Benign
-0.47
T
MutationAssessor
Pathogenic
3.3
M
PhyloP100
7.6
PrimateAI
Uncertain
0.76
T
PROVEAN
Pathogenic
-5.9
D
REVEL
Uncertain
0.53
Sift
Uncertain
0.012
D
Sift4G
Uncertain
0.018
D
Polyphen
1.0
D
Vest4
0.59
MutPred
0.39
Loss of methylation at K562 (P = 0.0863);
MVP
0.57
MPC
1.5
ClinPred
0.87
D
GERP RS
5.5
Varity_R
0.66
gMVP
0.68
Mutation Taster
=28/72
disease causing

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

Other links and lift over

dbSNP: rs774953382; hg19: chr2-171716279; API