8-27463554-T-A

Variant names:

• chr8-27463554-T-A
• rs1554514507
• NM_000742.4:c.889A>T

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP3_Moderate PP5

The NM_000742.4(CHRNA2):​c.889A>T​(p.Ile297Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: CHRNA2 NM_000742.4 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 2.65
• 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

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.91
• PP5: Variant 8-27463554-T-A is Pathogenic according to our data. Variant chr8-27463554-T-A is described in ClinVar as Pathogenic. ClinVar VariationId is 522582.Status of the report is no_assertion_criteria_provided, 0 stars.

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.889A>T	p.Ile297Phe	missense	Exon 6 of 7	NP_000733.2
	CHRNA2	NM_001282455.2		c.844A>T	p.Ile282Phe	missense	Exon 6 of 7	NP_001269384.1
	CHRNA2	NM_001347705.2		c.412A>T	p.Ile138Phe	missense	Exon 6 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.889A>T	p.Ile297Phe	missense	Exon 6 of 7	ENSP00000385026.1
	CHRNA2	ENST00000523695.5	TSL:1	n.*291A>T		non_coding_transcript_exon	Exon 6 of 7	ENSP00000430612.1
	CHRNA2	ENST00000523695.5	TSL:1	n.*291A>T		3_prime_UTR	Exon 6 of 7	ENSP00000430612.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy 4 Pathogenic:1

Apr 19, 2018

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.81
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.79	D
Eigen	Uncertain	0.32
Eigen_PC	Benign	0.18
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.45	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Uncertain	0.52	D
MutationAssessor	Pathogenic	3.9	H
PhyloP100		2.6
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-3.8	D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		0.99	D
Vest4		0.92
MutPred		0.53		Gain of methylation at K296 (P = 0.0665)
MVP		0.95
MPC		0.89
ClinPred		1.0	D
GERP RS		1.2
Varity_R		0.90
gMVP		0.93
Mutation Taster		=3/97	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: rs1554514507; hg19: chr8-27321071;