chr9-98293861-G-A

Variant names:

• chr9-98293861-G-A
• rs891861059
• NM_005458.8:c.2584C>T

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.2584C>T​(p.Pro862Ser) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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 (★). Synonymous variant affecting the same amino acid position (i.e. P862P) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: GABBR2 NM_005458.8 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.96
• 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=0.13975286).

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.2584C>T	p.Pro862Ser	missense	Exon 18 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.2584C>T	p.Pro862Ser	missense	Exon 18 of 19	ENSP00000259455.2
	GABBR2	ENST00000637410.1	TSL:5	n.2362C>T		non_coding_transcript_exon	Exon 18 of 19

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Epileptic encephalopathy Uncertain:1

Dec 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with serine, which is neutral and polar, at codon 862 of the GABBR2 protein (p.Pro862Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GABBR2-related conditions. ClinVar contains an entry for this variant (Variation ID: 462132). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.077
BayesDel_addAF	Benign	-0.054	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Benign	0.098	T
Eigen	Benign	-0.11
Eigen_PC	Benign	0.10
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.88	D
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.14	T
MetaSVM	Benign	-0.85	T
MutationAssessor	Benign	0.81	L
PhyloP100		5.0
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-0.27	N
REVEL	Benign	0.20
Sift	Uncertain	0.025	D
Sift4G	Uncertain	0.046	D
Polyphen		0.018	B
Vest4		0.38
MutPred		0.35		Loss of loop (P = 0.0603)
MVP		0.57
MPC		0.92
ClinPred		0.51	D
GERP RS		4.2
Varity_R		0.070
gMVP		0.45
Mutation Taster		=83/17	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: rs891861059; hg19: chr9-101056143; COSMIC: COSV52299574;