16-8735795-G-T

Position:

• chr16-8735795-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_020686.6(ABAT):​c.56G>T​(p.Arg19Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict 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. R19C) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: ABAT NM_020686.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -1.00

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 Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.101442486).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ABAT	NM_020686.6	c.56G>T	p.Arg19Leu	missense_variant	2/16	ENST00000268251.13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ABAT	ENST00000268251.13	c.56G>T	p.Arg19Leu	missense_variant	2/16	1	NM_020686.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1451710 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 721154

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Gamma-aminobutyric acid transaminase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 20, 2021

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 missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The leucine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. This variant has not been reported in the literature in individuals affected with ABAT-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with leucine at codon 19 of the ABAT protein (p.Arg19Leu). The arginine residue is weakly conserved and there is a moderate physicochemical difference between arginine and leucine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	-0.048	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	1.5
DANN	Benign	0.95
DEOGEN2	Benign	0.035	T;T;.;T;T;.;.;T;T
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.059	N
LIST_S2	Benign	0.66	.;T;T;T;T;T;T;.;T
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.10	T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.84	T
MutationAssessor	Benign	1.4	L;.;.;.;L;.;.;L;.
MutationTaster	Benign	0.66	D;N;N;N;N
PrimateAI	Benign	0.24	T
PROVEAN	Benign	-0.85	N;N;D;N;N;N;N;N;N
REVEL	Uncertain	0.34
Sift	Benign	0.35	T;T;T;T;T;T;T;T;T
Sift4G	Benign	0.26	T;T;D;T;T;T;T;T;T
Polyphen		0.0	B;.;.;.;B;.;.;B;.
Vest4		0.20
MutPred		0.48		Loss of MoRF binding (P = 0.003);.;Loss of MoRF binding (P = 0.003);Loss of MoRF binding (P = 0.003);Loss of MoRF binding (P = 0.003);Loss of MoRF binding (P = 0.003);.;Loss of MoRF binding (P = 0.003);Loss of MoRF binding (P = 0.003);
MVP		0.61
MPC		0.38
ClinPred		0.12	T
GERP RS		-1.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
Varity_R		0.042
gMVP		0.43

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr16-8829652;