chr1-2029147-T-C

Position:

• chr1-2029147-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000815.5(GABRD):​c.728T>C​(p.Leu243Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000717 in 1,394,058 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 7.2e-7 (0 hom.)
• Consequence: GABRD NM_000815.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.74

Genes affected

GABRD (HGNC:4084): (gamma-aminobutyric acid type A receptor subunit delta) Gamma-aminobutyric acid (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. The GABA-A receptor is generally pentameric and there are five types of subunits: alpha, beta, gamma, delta, and rho. This gene encodes the delta subunit. Mutations in this gene have been associated with susceptibility to generalized epilepsy with febrile seizures, type 5. Alternatively spliced transcript variants have been described for this gene, but their biological validity has not been determined. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GABRD	NM_000815.5	c.728T>C	p.Leu243Pro	missense_variant	7/9	ENST00000378585.7	NP_000806.2
GABRD	XM_017000936.2	c.1433T>C	p.Leu478Pro	missense_variant	6/8		XP_016856425.1
GABRD	XM_011541194.4	c.767T>C	p.Leu256Pro	missense_variant	7/9		XP_011539496.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GABRD	ENST00000378585.7	c.728T>C	p.Leu243Pro	missense_variant	7/9	1	NM_000815.5	ENSP00000367848	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD3 exomes AF: 0.00000648 AC: 1 AN: 154228 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 81508

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000163

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 7.17e-7 AC: 1 AN: 1394058 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 687934

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: 9.26e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Idiopathic generalized epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 23, 2017

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 (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with GABRD-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with proline at codon 243 of the GABRD protein (p.Leu243Pro). The leucine residue is highly conserved and there is a moderate physicochemical difference between leucine and proline. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	D;.;.;.;.
Eigen	Pathogenic	0.76
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D
M_CAP	Pathogenic	0.52	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Uncertain	0.69	D
MutationAssessor	Pathogenic	3.4	M;.;.;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-6.3	D;.;.;.;.
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;.;.;.;.
Sift4G	Pathogenic	0.0010	D;.;.;.;.
Polyphen		1.0	D;.;.;.;.
Vest4		0.99
MutPred		0.91		Loss of stability (P = 0.0282);.;Loss of stability (P = 0.0282);Loss of stability (P = 0.0282);.;
MVP		0.98
MPC		2.3
ClinPred		1.0	D
GERP RS		4.1
Varity_R		0.97
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1248355743; hg19: chr1-1960586;