2-170845254-C-T

Variant names:

• chr2-170845254-C-T
• rs16858977
• NM_000817.3:c.752-252C>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000817.3(GAD1):​c.752-252C>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000183 in 547,762 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000020 (0 hom.)
• Consequence: GAD1 NM_000817.3 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.77
• Publications: 2 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: Labcorp Genetics (formerly Invitae), G2P
• 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: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.78).

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAD1	NM_000817.3	MANE Select	c.752-252C>T		intron	N/A	NP_000808.2	Q99259-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAD1	ENST00000358196.8	TSL:1 MANE Select	c.752-252C>T		intron	N/A	ENSP00000350928.3	Q99259-1
	GAD1	ENST00000493875.5	TSL:1	n.752-252C>T		intron	N/A	ENSP00000434696.1	Q99259-4
	GAD1	ENST00000883273.1		c.752-252C>T		intron	N/A	ENSP00000553332.1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 151950 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000194

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000202 AC: 8 AN: 395812 Hom.: 0 AF XY: 0.0000238 AC XY: 5 AN XY: 210454

African (AFR) AF: 0.0000878 AC: 1 AN: 11396

American (AMR) AF: 0.00 AC: 0 AN: 18384

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 12196

East Asian (EAS) AF: 0.0000789 AC: 2 AN: 25338

South Asian (SAS) AF: 0.0000440 AC: 2 AN: 45466

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 22730

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 1708

European-Non Finnish (NFE) AF: 0.0000127 AC: 3 AN: 235872

Other (OTH) AF: 0.00 AC: 0 AN: 22722

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 151950 Hom.: 0 Cov.: 32 AF XY: 0.0000270 AC XY: 2 AN XY: 74190

African (AFR) AF: 0.00 AC: 0 AN: 41360

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.000194 AC: 1 AN: 5164

South Asian (SAS) AF: 0.00 AC: 0 AN: 4820

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10572

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67974

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 323

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.78
CADD	Benign	13
DANN	Benign	0.92
PhyloP100		1.8

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: rs16858977; hg19: chr2-171701764;