chr16-8768906-G-A

Position:

chr16-8768906-G-A

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BS1_SupportingBS2

The ENST00000268251.13(ABAT):c.749G>A(p.Arg250Gln) variant causes a missense change. The variant allele was found at a frequency of 0.0000421 in 1,613,996 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R250G) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000044 ( 2 hom. )

Consequence

ABAT
ENST00000268251.13 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 4.21

Variant links:

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -5 ACMG points.

BS1

Variant frequency is greater than expected in population amr. gnomad4_exome allele frequency = 0.0000438 (64/1461886) while in subpopulation AMR AF= 0.000246 (11/44722). AF 95% confidence interval is 0.000153. There are 2 homozygotes in gnomad4_exome. There are 40 alleles in male gnomad4_exome subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

BS2

High Homozygotes in GnomAdExome4 at 2 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ABAT	NM_020686.6 linkuse as main transcript	c.749G>A	p.Arg250Gln	missense_variant	11/16	ENST00000268251.13	NP_065737.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ABAT	ENST00000268251.13 linkuse as main transcript	c.749G>A	p.Arg250Gln	missense_variant	11/16	1	NM_020686.6	ENSP00000268251	P1

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152110

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000724

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000795

AC:

AN:

251484

Hom.:

AF XY:

0.0000956

AC XY:

AN XY:

135914

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000196

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000264

Gnomad OTH exome

AF:

0.000163

GnomAD4 exome

AF:

0.0000438

AC:

AN:

1461886

Hom.:

Cov.:

AF XY:

0.0000550

AC XY:

AN XY:

727244

show subpopulations

Gnomad4 AFR exome

AF:

0.0000597

Gnomad4 AMR exome

AF:

0.000246

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.000232

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000243

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152110

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74288

show subpopulations

Gnomad4 AFR

AF:

0.0000724

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000416

ExAC

AF:

0.000107

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Gamma-aminobutyric acid transaminase deficiency

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 04, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt ABAT protein function. ClinVar contains an entry for this variant (Variation ID: 460330). This variant has not been reported in the literature in individuals affected with ABAT-related conditions. This variant is present in population databases (rs375002262, gnomAD 0.03%). This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 250 of the ABAT protein (p.Arg250Gln). -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

not provided

Breakthrough Genomics, Breakthrough Genomics

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.074

BayesDel_addAF

Benign

-0.14

BayesDel_noAF

Benign

-0.14

CADD

Benign

DANN

Benign

0.94

DEOGEN2

Benign

0.18

T;T;.;T;T

Eigen

Benign

-0.42

Eigen_PC

Benign

-0.16

FATHMM_MKL

Uncertain

0.95

LIST_S2

Uncertain

0.94

.;D;D;.;D

M_CAP

Benign

0.065

MetaRNN

Benign

0.15

T;T;T;T;T

MetaSVM

Benign

-0.70

MutationAssessor

Benign

0.21

N;N;.;N;.

MutationTaster

Benign

1.0

D;D;D;D;D

PrimateAI

Uncertain

0.61

PROVEAN

Benign

-0.30

N;N;N;N;N

REVEL

Uncertain

0.36

Sift

Benign

0.73

T;T;T;T;T

Sift4G

Benign

0.82

T;T;T;T;T

Polyphen

0.0070

B;B;.;B;.

Vest4

0.39

MutPred

0.40

Loss of helix (P = 0.0558);Loss of helix (P = 0.0558);.;Loss of helix (P = 0.0558);Loss of helix (P = 0.0558);

MVP

0.70

MPC

0.36

ClinPred

0.063

GERP RS

4.8

Varity_R

0.084

gMVP

0.76

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.21

Details are displayed if max score is > 0.2

DS_AG_spliceai

0.21

Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over