rs12114756

chr8-27471103-G-T

Variant summary

Our verdict is Benign. Variant got -16 ACMG points: 0P and 16B. BP4_Strong BP6_Very_Strong BS2

The NM_000742.4(CHRNA2):c.-45C>A variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000485 in 1,569,574 control chromosomes in the GnomAD database, including 4 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0021 (2 hom., cov: 33)
  • Exomes 𝑓: 0.00032 (2 hom.)
• Consequence: CHRNA2 NM_000742.4 5_prime_UTR
• Clinical Significance: Benign criteria provided, multiple submitters, no conflicts B:2
• Conservation: PhyloP100: 0.406

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 -16 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.84).
• BP6: Variant 8-27471103-G-T is Benign according to our data. Variant chr8-27471103-G-T is described in ClinVar as [Benign]. Clinvar id is 136754.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS2: High AC in GnomAd at 312 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHRNA2	NM_000742.4	c.-45C>A		5_prime_UTR_variant	2/7	ENST00000407991.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHRNA2	ENST00000407991.3	c.-45C>A		5_prime_UTR_variant	2/7	5	NM_000742.4	P2

Frequencies

GnomAD3 genomes AF: 0.00205 AC: 312 AN: 152148 Hom.: 2 Cov.: 33

Gnomad AFR AF: 0.00710

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000327

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000132

Gnomad OTH AF: 0.00191

GnomAD3 exomes AF: 0.000614 AC: 151 AN: 245922 Hom.: 1 AF XY: 0.000413 AC XY: 55 AN XY: 133104

Gnomad AFR exome AF: 0.00743

Gnomad AMR exome AF: 0.000322

Gnomad ASJ exome AF: 0.000100

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000190

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.000315 AC: 447 AN: 1417308 Hom.: 2 Cov.: 23 AF XY: 0.000314 AC XY: 222 AN XY: 707748

Gnomad4 AFR exome AF: 0.00725

Gnomad4 AMR exome AF: 0.000316

Gnomad4 ASJ exome AF: 0.0000387

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000941

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000131

Gnomad4 OTH exome AF: 0.000679

GnomAD4 genome AF: 0.00207 AC: 315 AN: 152266 Hom.: 2 Cov.: 33 AF XY: 0.00189 AC XY: 141 AN XY: 74436

Gnomad4 AFR AF: 0.00715

Gnomad4 AMR AF: 0.000327

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000132

Gnomad4 OTH AF: 0.00189

Alfa AF: 0.00107 Hom.: 0

Bravo AF: 0.00212

Asia WGS AF: 0.00202 AC: 7 AN: 3478

ClinVar

Significance: Benign

Submissions summary: Benign:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:1

Benign, criteria provided, single submitter

clinical testing

GeneDx

Sep 10, 2013

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. -

Autosomal dominant nocturnal frontal lobe epilepsy 4 Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.84
Cadd	Benign	5.5
Dann	Benign	0.73

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: rs12114756; hg19: chr8-27328620;