chr9-98388933-T-C

Variant names:

• chr9-98388933-T-C
• rs1554698962
• NM_005458.8:c.1450A>G

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_005458.8(GABBR2):​c.1450A>G​(p.Ile484Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,332 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GABBR2 NM_005458.8 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.99
• Publications: 0 publications found

Genes affected

GABBR2 (HGNC:4507): (gamma-aminobutyric acid type B receptor subunit 2) The multi-pass membrane protein encoded by this gene belongs to the G-protein coupled receptor 3 family and GABA-B receptor subfamily. The GABA-B receptors inhibit neuronal activity through G protein-coupled second-messenger systems, which regulate the release of neurotransmitters, and the activity of ion channels and adenylyl cyclase. This receptor subunit forms an active heterodimeric complex with GABA-B receptor subunit 1, neither of which is effective on its own. Allelic variants of this gene have been associated with nicotine dependence.[provided by RefSeq, Jan 2010]

GABBR2 Gene-Disease associations (from GenCC):

• developmental and epileptic encephalopathy, 59

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• neurodevelopmental disorder with poor language and loss of hand skills

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• atypical Rett syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.21611032).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005458.8. 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
	GABBR2	NM_005458.8	MANE Select	c.1450A>G	p.Ile484Val	missense	Exon 10 of 19	NP_005449.5

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GABBR2	ENST00000259455.4	TSL:1 MANE Select	c.1450A>G	p.Ile484Val	missense	Exon 10 of 19	ENSP00000259455.2
	GABBR2	ENST00000637410.1	TSL:5	n.1228A>G		non_coding_transcript_exon	Exon 10 of 19
	GABBR2	ENST00000634314.1	TSL:3	n.-46A>G		upstream_gene	N/A

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461332 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727016

African (AFR) AF: 0.00 AC: 0 AN: 33464

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86210

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111564

Other (OTH) AF: 0.00 AC: 0 AN: 60372

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Epileptic encephalopathy Uncertain:1

May 03, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a GABBR2-related disease. This sequence change replaces isoleucine with valine at codon 484 of the GABBR2 protein (p.Ile484Val). The isoleucine residue is highly conserved and there is a small physicochemical difference between isoleucine and valine.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Benign	-0.037	T
BayesDel_noAF	Benign	-0.29
CADD	Benign	20
DANN	Benign	0.80
DEOGEN2	Benign	0.067	T
Eigen	Benign	-0.31
Eigen_PC	Benign	-0.13
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.76	T
M_CAP	Benign	0.011	T
MetaRNN	Benign	0.22	T
MetaSVM	Benign	-0.90	T
MutationAssessor	Benign	0.46	N
PhyloP100		6.0
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	0.27	N
REVEL	Benign	0.26
Sift	Benign	0.81	T
Sift4G	Benign	0.51	T
Polyphen		0.0010	B
Vest4		0.39
MutPred		0.56		Gain of sheet (P = 0.0344)
MVP		0.45
MPC		0.76
ClinPred		0.53	D
GERP RS		3.7
Varity_R		0.074
gMVP		0.35
Mutation Taster		=60/40	polymorphism

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: rs1554698962; hg19: chr9-101151215;