rs754992449

Positions:

• chr1-154571715-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 6P and 4B. PM2 PP3_Strong BS2

The NM_000748.3(CHRNB2):​c.892G>A​(p.Gly298Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,858 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. 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. G298V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: CHRNB2 NM_000748.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.95

Genes affected

CHRNB2 (HGNC:1962): (cholinergic receptor nicotinic beta 2 subunit) Neuronal acetylcholine receptors are homo- or heteropentameric complexes composed of homologous alpha and beta subunits. They belong to a superfamily of ligand-gated ion channels which allow the flow of sodium and potassium across the plasma membrane in response to ligands such as acetylcholine and nicotine. This gene encodes one of several beta subunits. Mutations in this gene are associated with autosomal dominant nocturnal frontal lobe epilepsy. [provided by RefSeq, Jul 2008]

CHRNB2 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.96
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNB2	NM_000748.3	c.892G>A	p.Gly298Ser	missense_variant	5/6	ENST00000368476.4	NP_000739.1
CHRNB2	XM_017000180.3	c.382G>A	p.Gly128Ser	missense_variant	2/3		XP_016855669.1
CHRNB2	XR_001736952.3	n.1159G>A		non_coding_transcript_exon_variant	5/7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHRNB2	ENST00000368476.4	c.892G>A	p.Gly298Ser	missense_variant	5/6	1	NM_000748.3	ENSP00000357461.3
CHRNB2	ENST00000637900.1	c.898G>A	p.Gly300Ser	missense_variant	5/6	5		ENSP00000490474.1
CHRNB2	ENST00000636034.1	n.892G>A		non_coding_transcript_exon_variant	5/9	5		ENSP00000489703.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251216 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135778

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000578

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: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461858 Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2 AN XY: 727230

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.0000247 AC: 3

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 06, 2022

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 298 of the CHRNB2 protein (p.Gly298Ser). 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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt CHRNB2 protein function. ClinVar contains an entry for this variant (Variation ID: 569750). This variant has not been reported in the literature in individuals affected with CHRNB2-related conditions. This variant is present in population databases (rs754992449, gnomAD 0.006%). -

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 13, 2023

The c.892G>A (p.G298S) alteration is located in exon 5 (coding exon 5) of the CHRNB2 gene. This alteration results from a G to A substitution at nucleotide position 892, causing the glycine (G) at amino acid position 298 to be replaced by a serine (S). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.69
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.40
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;.
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D
M_CAP	Pathogenic	0.40	D
MetaRNN	Pathogenic	0.96	D;D
MetaSVM	Uncertain	0.78	D
MutationAssessor	Pathogenic	3.3	M;.
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-5.8	D;.
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0050	D;.
Sift4G	Uncertain	0.012	D;.
Polyphen		1.0	D;.
Vest4		0.73
MutPred		0.83		Gain of ubiquitination at K299 (P = 0.1111);.;
MVP		0.95
MPC		2.3
ClinPred		0.99	D
GERP RS		4.0
Varity_R		0.90
gMVP		0.95

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

LitVar

Other links and lift over

dbSNP: rs754992449; hg19: chr1-154544191;