rs149855547

chr16-8772827-C-T

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 2P and 8B. PM2 BP4_Moderate BP6 BP7 BS1

The NM_020686.6(ABAT):c.864C>T(p.Ala288=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0002 in 1,614,008 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 31)
  • Exomes 𝑓: 0.00021 (1 hom.)
• Consequence: ABAT NM_020686.6 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: -2.63

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]

ACMG classification

Verdict is Likely_benign. Variant got -6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.44).
• BP6: Variant 16-8772827-C-T is Benign according to our data. Variant chr16-8772827-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 321080.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.
• BP7: Synonymous conserved (PhyloP=-2.63 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.000138 (21/152140) while in subpopulation EAS AF= 0.00193 (10/5170). AF 95% confidence interval is 0.00105. There are 0 homozygotes in gnomad4. There are 11 alleles in male gnomad4 subpopulation. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ABAT	NM_020686.6	c.864C>T	p.Ala288=	synonymous_variant	12/16	ENST00000268251.13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ABAT	ENST00000268251.13	c.864C>T	p.Ala288=	synonymous_variant	12/16	1	NM_020686.6	P1

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152022 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00193

Gnomad SAS AF: 0.000415

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000132

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000123 AC: 31 AN: 251466 Hom.: 0 AF XY: 0.000118 AC XY: 16 AN XY: 135912

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000578

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000381

Gnomad SAS exome AF: 0.000490

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000352

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.000206 AC: 301 AN: 1461868 Hom.: 1 Cov.: 32 AF XY: 0.000212 AC XY: 154 AN XY: 727236

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000671

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00521

Gnomad4 SAS exome AF: 0.000278

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000531

Gnomad4 OTH exome AF: 0.000116

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152140 Hom.: 0 Cov.: 31 AF XY: 0.000148 AC XY: 11 AN XY: 74378

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00193

Gnomad4 SAS AF: 0.000415

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000132

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000225 Hom.: 0

Bravo AF: 0.0000869

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.00

EpiControl AF: 0.000119

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Gamma-aminobutyric acid transaminase deficiency Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -
Likely benign, criteria provided, single submitter	clinical testing	Invitae	Jan 22, 2024	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
Cadd	Benign	0.17
Dann	Benign	0.88
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

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

LitVar

Other links and lift over

dbSNP: rs149855547; hg19: chr16-8866684; COSMIC: COSV99191030; COSMIC: COSV99191030;