16-8768960-G-T

Variant names:

• chr16-8768960-G-T
• rs570490857
• NM_020686.6:c.803G>T

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_020686.6(ABAT):​c.803G>T​(p.Arg268Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R268H) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: ABAT NM_020686.6 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 8.11
• 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, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, PanelApp Australia, Orphanet, G2P
• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.9

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ABAT	NM_020686.6	MANE Select	c.803G>T	p.Arg268Leu	missense	Exon 11 of 16	NP_065737.2
	ABAT	NM_001386615.1		c.899G>T	p.Arg300Leu	missense	Exon 12 of 17	NP_001373544.1
	ABAT	NM_001386616.1		c.803G>T	p.Arg268Leu	missense	Exon 11 of 16	NP_001373545.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ABAT	ENST00000268251.13	TSL:1 MANE Select	c.803G>T	p.Arg268Leu	missense	Exon 11 of 16	ENSP00000268251.8
	ABAT	ENST00000569156.5	TSL:1	c.803G>T	p.Arg268Leu	missense	Exon 11 of 16	ENSP00000454963.1
	ABAT	ENST00000566590.5	TSL:1	n.*543G>T		non_coding_transcript_exon	Exon 10 of 15	ENSP00000455198.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.31
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.66	D
Eigen	Pathogenic	0.79
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Uncertain	0.40	D
MutationAssessor	Pathogenic	2.9	M
PhyloP100		8.1
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.9	D
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0050	D
Polyphen		1.0	D
Vest4		0.81
MutPred		0.61		Loss of helix (P = 0.0072)
MVP		0.88
MPC		0.81
ClinPred		1.0	D
GERP RS		5.7
Varity_R		0.73
gMVP		0.93

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

Other links and lift over

dbSNP: rs570490857; hg19: chr16-8862817;