16-8781358-G-A

Variant summary

Our verdict is Benign. Variant got -7 ACMG points: 2P and 9B. PM2 BP4_Strong BP6 BS1

The ENST00000569156.5(ABAT):c.1490G>A(p.Arg497His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000979 in 1,614,142 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 10/13 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R497C) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000085 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000099 (0 hom.)
• Consequence: ABAT ENST00000569156.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: -1.82

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]

TMEM186 (HGNC:24530): (transmembrane protein 186) This gene encodes a potential transmembrane protein. [provided by RefSeq, Dec 2012]

ACMG classification

Verdict is Benign. Variant got -7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.012194216).
• BP6: Variant 16-8781358-G-A is Benign according to our data. Variant chr16-8781358-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 887492.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.0000854 (13/152264) while in subpopulation SAS AF= 0.00207 (10/4824). AF 95% confidence interval is 0.00112. There are 0 homozygotes in gnomad4. There are 9 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ABAT	NM_020686.6	c.1431G>A	p.Thr477=	synonymous_variant	16/16	ENST00000268251.13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ABAT	ENST00000268251.13	c.1431G>A	p.Thr477=	synonymous_variant	16/16	1	NM_020686.6	P1

Frequencies

GnomAD3 genomes AF: 0.0000854 AC: 13 AN: 152146 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: 0.000577

Gnomad SAS AF: 0.00207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000207 AC: 52 AN: 251482 Hom.: 0 AF XY: 0.000265 AC XY: 36 AN XY: 135912

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000326

Gnomad SAS exome AF: 0.00147

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000992 AC: 145 AN: 1461878 Hom.: 0 Cov.: 34 AF XY: 0.000124 AC XY: 90 AN XY: 727240

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.00146

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000809

Gnomad4 OTH exome AF: 0.0000662

GnomAD4 genome AF: 0.0000854 AC: 13 AN: 152264 Hom.: 0 Cov.: 32 AF XY: 0.000121 AC XY: 9 AN XY: 74438

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000578

Gnomad4 SAS AF: 0.00207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000434 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.000189 AC: 23

Asia WGS AF: 0.00144 AC: 5 AN: 3478

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 27, 2024	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Uncertain	-0.060
Cadd	Benign	5.3
Dann	Benign	0.82
DEOGEN2	Benign	0.0097	T
FATHMM_MKL	Benign	0.085	N
LIST_S2	Benign	0.49	T
M_CAP	Benign	0.0084	T
MetaRNN	Benign	0.012	T
MutationTaster	Benign	1.0	D;D;D;D;N
PROVEAN	Benign	-0.52	N
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.086
MVP		0.88
GERP RS		-8.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs573157071; hg19: chr16-8875215;