20-63350376-GCG-ACC

Variant names:

• chr20-63350376-GCG-ACC
• NM_000744.7:c.1033_1035delCGCinsGGT
• CHRNA4 p.Arg345Gly

Variant summary

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

The NM_000744.7(CHRNA4):​c.1033_1035delCGCinsGGT​(p.Arg345Gly) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R345H) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CHRNA4 NM_000744.7 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.82
• Publications: 0 publications found

Genes affected

CHRNA4 (HGNC:1958): (cholinergic receptor nicotinic alpha 4 subunit) This gene encodes a nicotinic acetylcholine receptor, which belongs to a superfamily of ligand-gated ion channels that play a role in fast signal transmission at synapses. These pentameric receptors can bind acetylcholine, which causes an extensive change in conformation that leads to the opening of an ion-conducting channel across the plasma membrane. This protein is an integral membrane receptor subunit that can interact with either nAChR beta-2 or nAChR beta-4 to form a functional receptor. Mutations in this gene cause nocturnal frontal lobe epilepsy type 1. Polymorphisms in this gene that provide protection against nicotine addiction have been described. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2012]

CHRNA4 Gene-Disease associations (from GenCC):

• autosomal dominant nocturnal frontal lobe epilepsy 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• familial sleep-related hypermotor epilepsy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• autosomal dominant nocturnal frontal lobe epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000744.7. 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
	CHRNA4	NM_000744.7	MANE Select	c.1033_1035delCGCinsGGT	p.Arg345Gly	missense	N/A	NP_000735.1	P43681-1
	CHRNA4	NM_001256573.2		c.505_507delCGCinsGGT	p.Arg169Gly	missense	N/A	NP_001243502.1	Q4VAQ3
	CHRNA4	NR_046317.2		n.1242_1244delCGCinsGGT		non_coding_transcript_exon	Exon 5 of 6

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNA4	ENST00000370263.9	TSL:1 MANE Select	c.1033_1035delCGCinsGGT	p.Arg345Gly	missense	N/A	ENSP00000359285.4	P43681-1
	CHRNA4	ENST00000463705.5	TSL:1	n.1681_1683delCGCinsGGT		non_coding_transcript_exon	Exon 4 of 5
	CHRNA4	ENST00000467563.3	TSL:1	n.1103_1105delCGCinsGGT		non_coding_transcript_exon	Exon 5 of 6

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		4.8

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr20-61981728;