rs143536618

Positions:

• chr8-27463759-G-A

Variant summary

Our verdict is Benign. Variant got -17 ACMG points: 0P and 17B. BP4_Strong BP6_Very_Strong BP7 BS2

The NM_000742.4(CHRNA2):​c.684C>T​(p.Ser228=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00015 in 1,614,130 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00067 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000096 (0 hom.)
• Consequence: CHRNA2 NM_000742.4 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:4
• Conservation: PhyloP100: -1.02

Genes affected

CHRNA2 (HGNC:1956): (cholinergic receptor nicotinic alpha 2 subunit) Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels formed by a pentameric arrangement of alpha and beta subunits to create distinct muscle and neuronal receptors. Neuronal receptors are found throughout the peripheral and central nervous system where they are involved in fast synaptic transmission. This gene encodes an alpha subunit that is widely expressed in the brain. The proposed structure for nAChR subunits is a conserved N-terminal extracellular domain followed by three conserved transmembrane domains, a variable cytoplasmic loop, a fourth conserved transmembrane domain, and a short C-terminal extracellular region. Mutations in this gene cause autosomal dominant nocturnal frontal lobe epilepsy type 4. Single nucleotide polymorphisms (SNPs) in this gene have been associated with nicotine dependence. [provided by RefSeq, Nov 2009]

ACMG classification

Verdict is Benign. Variant got -17 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.62).
• BP6: Variant 8-27463759-G-A is Benign according to our data. Variant chr8-27463759-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 377665.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr8-27463759-G-A is described in Lovd as [Likely_benign].
• BP7: Synonymous conserved (PhyloP=-1.02 with no splicing effect.
• BS2: High AC in GnomAd4 at 102 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNA2	NM_000742.4	c.684C>T	p.Ser228=	synonymous_variant	6/7	ENST00000407991.3	NP_000733.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHRNA2	ENST00000407991.3	c.684C>T	p.Ser228=	synonymous_variant	6/7	5	NM_000742.4	ENSP00000385026	P2

Frequencies

GnomAD3 genomes AF: 0.000670 AC: 102 AN: 152130 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00227

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000415

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00143

GnomAD3 exomes AF: 0.000258 AC: 65 AN: 251482 Hom.: 0 AF XY: 0.000265 AC XY: 36 AN XY: 135914

Gnomad AFR exome AF: 0.00265

Gnomad AMR exome AF: 0.0000578

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000555

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000958 AC: 140 AN: 1461882 Hom.: 0 Cov.: 33 AF XY: 0.000103 AC XY: 75 AN XY: 727240

Gnomad4 AFR exome AF: 0.00245

Gnomad4 AMR exome AF: 0.0000894

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000336

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000135

Gnomad4 OTH exome AF: 0.000149

GnomAD4 genome AF: 0.000670 AC: 102 AN: 152248 Hom.: 0 Cov.: 32 AF XY: 0.000658 AC XY: 49 AN XY: 74440

Gnomad4 AFR AF: 0.00226

Gnomad4 AMR AF: 0.000131

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000415

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00142

Alfa AF: 0.000229 Hom.: 0

Bravo AF: 0.000676

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:2

Benign, criteria provided, single submitter	clinical testing	GeneDx	Jul 13, 2015	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Likely benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Dec 29, 2017	- -

Autosomal dominant nocturnal frontal lobe epilepsy Benign:1

Benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 22, 2024

- -

Inborn genetic diseases Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 04, 2017

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.62
CADD	Benign	1.4
DANN	Benign	0.87

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: rs143536618; hg19: chr8-27321276;