chr8-42730639-G-A

Variant names:

• chr8-42730639-G-A
• rs774015181
• NM_000749.5:c.295G>A

Variant summary

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

The NM_000749.5(CHRNB3):​c.295G>A​(p.Gly99Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,457,444 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: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CHRNB3 NM_000749.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 10.0

Genes affected

CHRNB3 (HGNC:1963): (cholinergic receptor nicotinic beta 3 subunit) The nicotinic acetylcholine receptors (nAChRs) are members of a superfamily of ligand-gated ion channels that mediate fast signal transmission at synapses. The nAChRs are (hetero)pentamers composed of homologous subunits. The subunits that make up the muscle and neuronal forms of nAChRs are encoded by separate genes and have different primary structure. There are several subtypes of neuronal nAChRs that vary based on which homologous subunits are arranged around the central channel. They are classified as alpha-subunits if, like muscle alpha-1 (MIM 100690), they have a pair of adjacent cysteines as part of the presumed acetylcholine binding site. Subunits lacking these cysteine residues are classified as beta-subunits (Groot Kormelink and Luyten, 1997 [PubMed 9009220]). Elliott et al. (1996) [PubMed 8906617] stated that the proposed structure for each subunit is a conserved N-terminal extracellular domain followed by 3 conserved transmembrane domains, a variable cytoplasmic loop, a fourth conserved transmembrane domain, and a short C-terminal extracellular region.[supplied by OMIM, Apr 2010]

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, 0.977

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNB3	NM_000749.5	c.295G>A	p.Gly99Arg	missense_variant	Exon 4 of 6	ENST00000289957.3	NP_000740.1
CHRNB3	NM_001347717.2	c.73G>A	p.Gly25Arg	missense_variant	Exon 5 of 7		NP_001334646.1
CHRNB3	XM_011544390.3	c.-93G>A		5_prime_UTR_variant	Exon 2 of 4		XP_011542692.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNB3	ENST00000289957.3	c.295G>A	p.Gly99Arg	missense_variant	Exon 4 of 6	1	NM_000749.5	ENSP00000289957.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000802 AC: 2 AN: 249358 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 134876

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000590

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1457444 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 725114

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000450

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Nov 21, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.295G>A (p.G99R) alteration is located in exon 4 (coding exon 4) of the CHRNB3 gene. This alteration results from a G to A substitution at nucleotide position 295, causing the glycine (G) at amino acid position 99 to be replaced by an arginine (R). 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	Uncertain	0.37
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Pathogenic	0.28
CADD	Pathogenic	26
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.81	D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.78	T
M_CAP	Uncertain	0.11	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.82	D
MutationAssessor	Pathogenic	3.5	M
PrimateAI	Uncertain	0.68	T
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.81
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.89
MutPred		0.86		Gain of solvent accessibility (P = 0.0674);
MVP		0.97
MPC		0.94
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.84
gMVP		0.72

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: rs774015181; hg19: chr8-42585782;