rs1555551838

Variant names:

• chr17-7446846-A-G
• rs1555551838
• NM_000747.3:c.257A>G

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_000747.3(CHRNB1):​c.257A>G​(p.Tyr86Cys) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,554 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: 6.8e-7 (0 hom.)
• Consequence: CHRNB1 NM_000747.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.82
• Publications: 0 publications found

Genes affected

CHRNB1 (HGNC:1961): (cholinergic receptor nicotinic beta 1 subunit) The muscle acetylcholine receptor is composed of five subunits: two alpha subunits and one beta, one gamma, and one delta subunit. This gene encodes the beta subunit of the acetylcholine receptor. The acetylcholine receptor changes conformation upon acetylcholine binding leading to the opening of an ion-conducting channel across the plasma membrane. Mutations in this gene are associated with slow-channel congenital myasthenic syndrome. [provided by RefSeq, Jul 2008]

CHRNB1 Gene-Disease associations (from GenCC):

• congenital myasthenic syndrome 2C

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: G2P, PanelApp Australia, Labcorp Genetics (formerly Invitae), Ambry Genetics, Genomics England PanelApp
• congenital myasthenic syndrome 1A

  Inheritance: AD Classification: STRONG Submitted by: PanelApp Australia
• congenital myasthenic syndrome 2A

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Ambry Genetics
• postsynaptic congenital myasthenic syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.905

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNB1	NM_000747.3	c.257A>G	p.Tyr86Cys	missense_variant	Exon 4 of 11	ENST00000306071.7	NP_000738.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNB1	ENST00000306071.7	c.257A>G	p.Tyr86Cys	missense_variant	Exon 4 of 11	1	NM_000747.3	ENSP00000304290.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461554 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727072

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86236

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53246

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5720

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111928

Other (OTH) AF: 0.00 AC: 0 AN: 60386

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital myasthenic syndrome 2A Uncertain:1

Jul 18, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine with cysteine at codon 86 of the CHRNB1 protein (p.Tyr86Cys). The tyrosine residue is moderately conserved and there is a large physicochemical difference between tyrosine and cysteine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with CHRNB1-related disease. 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: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	Uncertain	0.49
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.66	D;.;.;.
Eigen	Pathogenic	0.76
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.90	D;D;D;D
MetaSVM	Uncertain	0.46	D
MutationAssessor	Uncertain	2.7	M;.;.;.
PhyloP100		5.8
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-7.4	D;.;D;.
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0030	D;.;D;.
Sift4G	Uncertain	0.0020	D;D;D;D
Polyphen		1.0	D;.;.;.
Vest4		0.82
MutPred		0.72		Loss of sheet (P = 0.1398);.;.;.;
MVP		0.94
MPC		1.4
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.88
gMVP		0.49
Mutation Taster		=62/38	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: rs1555551838; hg19: chr17-7350165;