NM_020686.6:c.668-3C>T

Variant names:

• chr16-8768822-C-T
• rs375716049
• NM_020686.6:c.668-3C>T

Variant summary

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

The NM_020686.6(ABAT):​c.668-3C>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000409 in 1,614,062 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000046 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000040 (0 hom.)
• Consequence: ABAT NM_020686.6 splice_region, intron
• Scores: Splicing: ADA: 0.001247
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.0490
• Publications: 0 publications found

Genes affected

ABAT (HGNC:23): (4-aminobutyrate aminotransferase) 4-aminobutyrate aminotransferase (ABAT) is responsible for catabolism of gamma-aminobutyric acid (GABA), an important, mostly inhibitory neurotransmitter in the central nervous system, into succinic semialdehyde. The active enzyme is a homodimer of 50-kD subunits complexed to pyridoxal-5-phosphate. The protein sequence is over 95% similar to the pig protein. GABA is estimated to be present in nearly one-third of human synapses. ABAT in liver and brain is controlled by 2 codominant alleles with a frequency in a Caucasian population of 0.56 and 0.44. The ABAT deficiency phenotype includes psychomotor retardation, hypotonia, hyperreflexia, lethargy, refractory seizures, and EEG abnormalities. Multiple alternatively spliced transcript variants encoding the same protein isoform have been found for this gene. [provided by RefSeq, Jul 2008]

ABAT Gene-Disease associations (from GenCC):

• GABA aminotransaminase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Orphanet
• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen

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=-0.64).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_020686.6. 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
	ABAT	NM_020686.6	MANE Select	c.668-3C>T		splice_region intron	N/A	NP_065737.2
	ABAT	NM_001386615.1		c.764-3C>T		splice_region intron	N/A	NP_001373544.1
	ABAT	NM_001386616.1		c.668-3C>T		splice_region intron	N/A	NP_001373545.1	H3BNQ7

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ABAT	ENST00000268251.13	TSL:1 MANE Select	c.668-3C>T		splice_region intron	N/A	ENSP00000268251.8	P80404
	ABAT	ENST00000569156.5	TSL:1	c.668-3C>T		splice_region intron	N/A	ENSP00000454963.1	H3BNQ7
	ABAT	ENST00000566590.5	TSL:1	n.*408-3C>T		splice_region intron	N/A	ENSP00000455198.1	H3BP84

Frequencies

GnomAD3 genomes AF: 0.0000460 AC: 7 AN: 152210 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.000103

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000318 AC: 8 AN: 251450 AF XY: 0.0000442

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: 0.0000703

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000404 AC: 59 AN: 1461852 Hom.: 0 Cov.: 32 AF XY: 0.0000413 AC XY: 30 AN XY: 727224

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

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.0000765 AC: 2 AN: 26136

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53398

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

European-Non Finnish (NFE) AF: 0.0000477 AC: 53 AN: 1111998

Other (OTH) AF: 0.0000497 AC: 3 AN: 60394

GnomAD4 genome AF: 0.0000460 AC: 7 AN: 152210 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74358

African (AFR) AF: 0.00 AC: 0 AN: 41438

American (AMR) AF: 0.00 AC: 0 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

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

European-Non Finnish (NFE) AF: 0.000103 AC: 7 AN: 68038

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

Alfa AF: 0.0000662 Hom.: 0

Bravo AF: 0.0000567

EpiCase AF: 0.000273

EpiControl AF: 0.000119

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	Gamma-aminobutyric acid transaminase deficiency (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.64
CADD	Benign	6.2
DANN	Benign	0.74
PhyloP100		0.049

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.0012
dbscSNV1_RF	Benign	0.16
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: rs375716049; hg19: chr16-8862679;