chr5-161854270-G-A

Variant names:

• chr5-161854270-G-A
• rs1554084012
• NM_001127644.2:c.187G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_001127644.2(GABRA1):​c.187G>A​(p.Glu63Lys) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 2/3 splice prediction tools predicting alterations to normal splicing. 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. E63A) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.4e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GABRA1 NM_001127644.2 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.32
• Publications: 0 publications found

Genes affected

GABRA1 (HGNC:4075): (gamma-aminobutyric acid type A receptor subunit alpha1) This gene encodes a gamma-aminobutyric acid (GABA) receptor. GABA is the major inhibitory neurotransmitter in the mammalian brain where it acts at GABA-A receptors, which are ligand-gated chloride channels. Chloride conductance of these channels can be modulated by agents such as benzodiazepines that bind to the GABA-A receptor. GABA-A receptors are pentameric, consisting of proteins from several subunit classes: alpha, beta, gamma, delta and rho. Mutations in this gene cause juvenile myoclonic epilepsy and childhood absence epilepsy type 4. Multiple transcript variants encoding the same protein have been identified for this gene. [provided by RefSeq, Jul 2008]

GABRA1 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy, 19

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• genetic developmental and epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• epilepsy, idiopathic generalized, susceptibility to, 13

  Inheritance: AD Classification: STRONG Submitted by: G2P
• Dravet syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• juvenile myoclonic epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 uncertain in NM_001127644.2
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001127644.2. 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
	GABRA1	NM_001127644.2	MANE Select	c.187G>A	p.Glu63Lys	missense splice_region	Exon 3 of 10	NP_001121116.1
	GABRA1	NM_000806.5		c.187G>A	p.Glu63Lys	missense splice_region	Exon 4 of 11	NP_000797.2
	GABRA1	NM_001127643.2		c.187G>A	p.Glu63Lys	missense splice_region	Exon 4 of 11	NP_001121115.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GABRA1	ENST00000393943.10	TSL:1 MANE Select	c.187G>A	p.Glu63Lys	missense splice_region	Exon 3 of 10	ENSP00000377517.4
	GABRA1	ENST00000023897.10	TSL:1	c.187G>A	p.Glu63Lys	missense splice_region	Exon 4 of 11	ENSP00000023897.6
	GABRA1	ENST00000428797.7	TSL:1	c.187G>A	p.Glu63Lys	missense splice_region	Exon 4 of 11	ENSP00000393097.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 7.44e-7 AC: 1 AN: 1344864 Hom.: 0 Cov.: 22 AF XY: 0.00 AC XY: 0 AN XY: 675522

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 31330

American (AMR) AF: 0.00 AC: 0 AN: 44530

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25342

East Asian (EAS) AF: 0.00 AC: 0 AN: 39066

South Asian (SAS) AF: 0.00 AC: 0 AN: 83790

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53358

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5544

European-Non Finnish (NFE) AF: 9.95e-7 AC: 1 AN: 1005420

Other (OTH) AF: 0.00 AC: 0 AN: 56484

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Jul 27, 2016

Genetic Services Laboratory, University of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.51
BayesDel_addAF	Uncertain	0.086	D
BayesDel_noAF	Benign	-0.11
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Benign	0.39	T
Eigen	Uncertain	0.49
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.15	D
MetaRNN	Uncertain	0.56	D
MetaSVM	Uncertain	-0.26	T
MutationAssessor	Benign	1.8	L
PhyloP100		9.3
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-1.1	N
REVEL	Uncertain	0.41
Sift	Benign	0.46	T
Sift4G	Benign	0.48	T
Polyphen		0.66	P
Vest4		0.78
MutPred		0.56		Gain of methylation at E63 (P = 0.014)
MVP		0.84
MPC		1.5
ClinPred		0.94	D
GERP RS		5.5
Varity_R		0.41
gMVP		0.85
Mutation Taster		=9/91	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.010		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: rs1554084012; hg19: chr5-161281276;