rs768297928

Positions:

• chr1-154571362-G-A
• chr1-154571362-G-C

Variant summary

Our verdict is Benign. Variant got -7 ACMG points: 0P and 7B. BP4_Moderate BS1_Supporting BS2

The NM_000748.3(CHRNB2):​c.539G>A​(p.Arg180His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000958 in 1,461,884 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign 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. R180L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: CHRNB2 NM_000748.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.24

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 Benign. Variant got -7 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.17734078).
• BS1: Variant frequency is greater than expected in population eas. gnomad4_exome allele frequency = 0.00000958 (14/1461884) while in subpopulation EAS AF= 0.000227 (9/39700). AF 95% confidence interval is 0.000118. There are 0 homozygotes in gnomad4_exome. There are 8 alleles in male gnomad4_exome subpopulation. Median coverage is 33. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAdExome4 at 14 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNB2	NM_000748.3	c.539G>A	p.Arg180His	missense_variant	5/6	ENST00000368476.4	NP_000739.1
CHRNB2	XM_017000180.3	c.29G>A	p.Arg10His	missense_variant	2/3		XP_016855669.1
CHRNB2	XR_001736952.3	n.806G>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.539G>A	p.Arg180His	missense_variant	5/6	1	NM_000748.3	ENSP00000357461.3
CHRNB2	ENST00000637900.1	c.545G>A	p.Arg182His	missense_variant	5/6	5		ENSP00000490474.1
CHRNB2	ENST00000636034.1	n.539G>A		non_coding_transcript_exon_variant	5/9	5		ENSP00000489703.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251418 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135900

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.0000992

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461884 Hom.: 0 Cov.: 33 AF XY: 0.0000110 AC XY: 8 AN XY: 727244

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.0000765

Gnomad4 EAS exome AF: 0.000227

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 21, 2020

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 tolerated, 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 CHRNB2-related disease. This variant is present in population databases (rs768297928, ExAC 0.001%). This sequence change replaces arginine with histidine at codon 180 of the CHRNB2 protein (p.Arg180His). The arginine residue is moderately conserved and there is a small physicochemical difference between arginine and histidine. 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 v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.093
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.34
CADD	Benign	23
DANN	Uncertain	0.99
DEOGEN2	Benign	0.30	T;.
Eigen	Benign	-0.28
Eigen_PC	Benign	-0.12
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.18	T;T
MetaSVM	Benign	-0.92	T
MutationAssessor	Benign	-0.11	N;.
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	0.40	N;.
REVEL	Benign	0.16
Sift	Benign	0.18	T;.
Sift4G	Benign	0.18	T;.
Polyphen		0.057	B;.
Vest4		0.26
MutPred		0.64		Loss of sheet (P = 0.0817);.;
MVP		0.69
MPC		1.4
ClinPred		0.30	T
GERP RS		3.5
Varity_R		0.14
gMVP		0.80

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: rs768297928; hg19: chr1-154543838; COSMIC: COSV63808975; COSMIC: COSV63808975;