NM_000742.4:c.836T>A

Variant names:

• chr8-27463607-A-T
• rs104894063
• NM_000742.4:c.836T>A

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_000742.4(CHRNA2):​c.836T>A​(p.Ile279Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I279V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: CHRNA2 NM_000742.4 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1 O:1
• Conservation: PhyloP100: 9.32
• Publications: 16 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_pathogenic. The variant received 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.978
• PP5: Variant 8-27463607-A-T is Pathogenic according to our data. Variant chr8-27463607-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 17504.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNA2	NM_000742.4	c.836T>A	p.Ile279Asn	missense_variant	Exon 6 of 7	ENST00000407991.3	NP_000733.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNA2	ENST00000407991.3	c.836T>A	p.Ile279Asn	missense_variant	Exon 6 of 7	5	NM_000742.4	ENSP00000385026.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: no assertion criteria provided

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy 4 Pathogenic:1 Other:1

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Aug 01, 2006

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.94	D;.;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.97	D;D;D
M_CAP	Pathogenic	0.63	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	0.92	D
MutationAssessor	Pathogenic	4.7	H;.;.
PhyloP100		9.3
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-6.7	D;.;D
REVEL	Pathogenic	0.88
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.97
MutPred		0.88		Loss of stability (P = 0.0809);.;.;
MVP		0.97
MPC		0.98
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.97
gMVP		0.99
Mutation Taster		=1/99	disease causing (ClinVar)

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: rs104894063; hg19: chr8-27321124;