rs891398

Variant names:

• chr8-27467305-T-A
• rs891398
• NM_000742.4:c.373A>T

Your query was ambiguous. Multiple possible variants found:

• chr8-27467305-T-A
• chr8-27467305-T-C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000742.4(CHRNA2):​c.373A>T​(p.Thr125Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,222 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T125A) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CHRNA2 NM_000742.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.868
• Publications: 0 publications found

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]

CHRNA2 Gene-Disease associations (from GenCC):

• autosomal dominant nocturnal frontal lobe epilepsy 4

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: G2P, Illumina, Labcorp Genetics (formerly Invitae)
• autosomal dominant nocturnal frontal lobe epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial sleep-related hypermotor epilepsy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• benign familial infantile epilepsy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.04096231).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000742.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNA2	NM_000742.4	MANE Select	c.373A>T	p.Thr125Ser	missense	Exon 5 of 7	NP_000733.2
	CHRNA2	NM_001282455.2		c.328A>T	p.Thr110Ser	missense	Exon 5 of 7	NP_001269384.1
	CHRNA2	NM_001347705.2		c.-100A>T		5_prime_UTR	Exon 5 of 7	NP_001334634.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNA2	ENST00000407991.3	TSL:5 MANE Select	c.373A>T	p.Thr125Ser	missense	Exon 5 of 7	ENSP00000385026.1
	CHRNA2	ENST00000520600.1	TSL:1	n.213A>T		non_coding_transcript_exon	Exon 1 of 2
	CHRNA2	ENST00000523695.5	TSL:1	n.373A>T		non_coding_transcript_exon	Exon 5 of 7	ENSP00000430612.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461222 Hom.: 0 Cov.: 40 AF XY: 0.00 AC XY: 0 AN XY: 727006

African (AFR) AF: 0.00 AC: 0 AN: 33452

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86244

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111436

Other (OTH) AF: 0.00 AC: 0 AN: 60368

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.058
BayesDel_addAF	Benign	-0.25	T
BayesDel_noAF	Benign	-0.59
CADD	Benign	10
DANN	Benign	0.33
DEOGEN2	Benign	0.15	T
Eigen	Benign	-1.3
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.051	N
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.041	T
MetaSVM	Benign	-0.90	T
MutationAssessor	Benign	-1.4	N
PhyloP100		0.87
PrimateAI	Benign	0.39	T
PROVEAN	Benign	1.1	N
REVEL	Benign	0.13
Sift	Benign	0.74	T
Sift4G	Benign	0.48	T
Polyphen		0.0	B
Vest4		0.080
MutPred		0.27		Gain of relative solvent accessibility (P = 0.1571)
MVP		0.65
MPC		0.16
ClinPred		0.048	T
GERP RS		3.5
Varity_R		0.056
gMVP		0.18
Mutation Taster		=95/5	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: rs891398; hg19: chr8-27324822;