chr2-170852781-G-C

Variant names:

• chr2-170852781-G-C
• rs143058194
• NM_000817.3:c.1252G>C

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000817.3(GAD1):​c.1252G>C​(p.Val418Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,826 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 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. V418F) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GAD1 NM_000817.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.75
• Publications: 0 publications found

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)

ACMG classification

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

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.28518963).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000817.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAD1	NM_000817.3	MANE Select	c.1252G>C	p.Val418Leu	missense	Exon 13 of 17	NP_000808.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAD1	ENST00000358196.8	TSL:1 MANE Select	c.1252G>C	p.Val418Leu	missense	Exon 13 of 17	ENSP00000350928.3
	GAD1	ENST00000488724.5	TSL:1	n.352G>C		non_coding_transcript_exon	Exon 2 of 6
	GAD1	ENST00000493875.5	TSL:1	n.*86G>C		non_coding_transcript_exon	Exon 13 of 17	ENSP00000434696.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461826 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727232

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111952

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Benign	-0.17	T
BayesDel_noAF	Benign	-0.48
CADD	Benign	16
DANN	Benign	0.93
DEOGEN2	Benign	0.24	T
Eigen	Benign	-0.50
Eigen_PC	Benign	-0.32
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.89	D
M_CAP	Benign	0.014	T
MetaRNN	Benign	0.29	T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.80	N
PhyloP100		1.8
PrimateAI	Uncertain	0.48	T
PROVEAN	Benign	-0.25	N
REVEL	Benign	0.066
Sift	Benign	0.67	T
Sift4G	Benign	0.66	T
Polyphen		0.019	B
Vest4		0.45
MutPred		0.74		Loss of methylation at K419 (P = 0.0354)
MVP		0.51
MPC		0.59
ClinPred		0.36	T
GERP RS		3.1
Varity_R		0.29
gMVP		0.80
Mutation Taster		=60/40	polymorphism

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

Other links and lift over

dbSNP: rs143058194; hg19: chr2-171709291;