rs768590131

Variant names:

• chr8-27463742-A-G
• rs768590131
• NM_000742.4:c.701T>C

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP6 BS2

The NM_000742.4(CHRNA2):​c.701T>C​(p.Val234Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000434 in 1,613,888 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V234I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: CHRNA2 NM_000742.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 9.32
• Publications: 1 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
• epilepsy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• BP6: Variant 8-27463742-A-G is Benign according to our data. Variant chr8-27463742-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 476994.
• BS2: High AC in GnomAdExome4 at 6 AD gene.

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNA2	NM_000742.4	MANE Select	c.701T>C	p.Val234Ala	missense	Exon 6 of 7	NP_000733.2	Q15822-1
	CHRNA2	NM_001282455.2		c.656T>C	p.Val219Ala	missense	Exon 6 of 7	NP_001269384.1	Q15822-2
	CHRNA2	NM_001347705.2		c.224T>C	p.Val75Ala	missense	Exon 6 of 7	NP_001334634.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNA2	ENST00000407991.3	TSL:5 MANE Select	c.701T>C	p.Val234Ala	missense	Exon 6 of 7	ENSP00000385026.1	Q15822-1
	CHRNA2	ENST00000523695.5	TSL:1	n.*103T>C		non_coding_transcript_exon	Exon 6 of 7	ENSP00000430612.1	E5RJ54
	CHRNA2	ENST00000523695.5	TSL:1	n.*103T>C		3_prime_UTR	Exon 6 of 7	ENSP00000430612.1	E5RJ54

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151996 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.00

Gnomad OTH AF: 0.000480

GnomAD2 exomes AF: 0.00000795 AC: 2 AN: 251482 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461892 Hom.: 0 Cov.: 33 AF XY: 0.00000550 AC XY: 4 AN XY: 727246

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

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: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1112012

Other (OTH) AF: 0.0000497 AC: 3 AN: 60396

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151996 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74238

African (AFR) AF: 0.00 AC: 0 AN: 41384

American (AMR) AF: 0.00 AC: 0 AN: 15262

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5186

South Asian (SAS) AF: 0.00 AC: 0 AN: 4814

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10600

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 314

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67974

Other (OTH) AF: 0.000480 AC: 1 AN: 2084

Alfa AF: 0.0000508 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	1	Autosomal dominant nocturnal frontal lobe epilepsy (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.46
BayesDel_addAF	Benign	-0.0066	T
BayesDel_noAF	Benign	-0.23
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D
Eigen	Uncertain	0.20
Eigen_PC	Uncertain	0.33
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.93	D
M_CAP	Uncertain	0.089	D
MetaRNN	Uncertain	0.44	T
MetaSVM	Uncertain	-0.26	T
MutationAssessor	Uncertain	2.3	M
PhyloP100		9.3
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-3.4	D
REVEL	Uncertain	0.43
Sift	Uncertain	0.024	D
Sift4G	Uncertain	0.035	D
Polyphen		0.011	B
Vest4		0.32
MutPred		0.60		Gain of sheet (P = 0.1208)
MVP		0.83
MPC		0.39
ClinPred		0.88	D
GERP RS		5.0
Varity_R		0.49
gMVP		0.62
Mutation Taster		=56/44	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: rs768590131; hg19: chr8-27321259;