Genetic Variant NM_020686.6:c.978C>T (chr16-8774913-C-T) – ACMG Classification: Likely_benign (-4 pts)

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 2P and 6B. PM2BP4_StrongBP6BP7

The NM_020686.6(ABAT):c.978C>T(p.Asp326Asp) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000359 in 1,613,890 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000039 ( 0 hom. )

Consequence

ABAT
NM_020686.6 synonymous

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1B:1

Conservation

PhyloP100: -1.13

Publications

1 publications found

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 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

ABAT links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.55).

BP6

Variant 16-8774913-C-T is Benign according to our data. Variant chr16-8774913-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 460331.

BP7

Synonymous conserved (PhyloP=-1.13 with no splicing effect.

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

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
ABAT	NM_020686.6	MANE Select	c.978C>T	p.Asp326Asp	synonymous	Exon 13 of 16	NP_065737.2
ABAT	NM_001386615.1		c.1074C>T	p.Asp358Asp	synonymous	Exon 14 of 17	NP_001373544.1
ABAT	NM_001386616.1		c.978C>T	p.Asp326Asp	synonymous	Exon 13 of 16	NP_001373545.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
ABAT	ENST00000268251.13	TSL:1 MANE Select	c.978C>T	p.Asp326Asp	synonymous	Exon 13 of 16	ENSP00000268251.8
ABAT	ENST00000569156.5	TSL:1	c.978C>T	p.Asp326Asp	synonymous	Exon 13 of 16	ENSP00000454963.1
ABAT	ENST00000566590.5	TSL:1	n.*718C>T		non_coding_transcript_exon	Exon 12 of 15	ENSP00000455198.1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152128

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251422

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000390

AC:

AN:

1461762

Hom.:

Cov.:

AF XY:

0.0000385

AC XY:

AN XY:

727192

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000232

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5730

European-Non Finnish (NFE)

AF:

0.0000459

AC:

AN:

1111958

Other (OTH)

AF:

0.0000331

AC:

AN:

60384

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.467

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152128

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74302

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15262

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10604

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000508

Hom.:

Bravo

AF:

0.0000227

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

ClinVar submissions as Germline

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

Gamma-aminobutyric acid transaminase deficiency (2)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.55

CADD

Benign

0.24

(source)

DANN

Benign

0.61

PhyloP100

-1.1

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

2.7

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over