20-63359551-G-A

Position:

• chr20-63359551-G-A

Variant summary

Our verdict is Benign. Variant got -16 ACMG points: 0P and 16B. BP4_Strong BP6_Very_Strong BS2

The NM_001256573.2(CHRNA4):​c.-322C>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00018 in 1,612,656 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00048 (0 hom., cov: 34)
  • Exomes 𝑓: 0.00015 (0 hom.)
• Consequence: CHRNA4 NM_001256573.2 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:5
• Conservation: PhyloP100: -1.15

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]

ACMG classification

Verdict is Benign. Variant got -16 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.49).
• BP6: Variant 20-63359551-G-A is Benign according to our data. Variant chr20-63359551-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 377669.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr20-63359551-G-A is described in Lovd as [Likely_benign].
• BS2: High AC in GnomAd4 at 73 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNA4	NM_000744.7	c.225C>T	p.Asp75Asp	synonymous_variant	2/6	ENST00000370263.9	NP_000735.1
CHRNA4	NM_001256573.2	c.-322C>T		5_prime_UTR_premature_start_codon_gain_variant	2/6		NP_001243502.1
CHRNA4	NM_001256573.2	c.-322C>T		5_prime_UTR_variant	2/6		NP_001243502.1
CHRNA4	NR_046317.2	n.409C>T		non_coding_transcript_exon_variant	2/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHRNA4	ENST00000370263.9	c.225C>T	p.Asp75Asp	synonymous_variant	2/6	1	NM_000744.7	ENSP00000359285.4

Frequencies

GnomAD3 genomes AF: 0.000466 AC: 71 AN: 152222 Hom.: 0 Cov.: 34

Gnomad AFR AF: 0.00121

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000196

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: 0.000235

Gnomad OTH AF: 0.000958

GnomAD3 exomes AF: 0.000164 AC: 41 AN: 249774 Hom.: 0 AF XY: 0.000147 AC XY: 20 AN XY: 135614

Gnomad AFR exome AF: 0.000808

Gnomad AMR exome AF: 0.0000579

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000222

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.000149 AC: 218 AN: 1460316 Hom.: 0 Cov.: 38 AF XY: 0.000157 AC XY: 114 AN XY: 726446

Gnomad4 AFR exome AF: 0.00105

Gnomad4 AMR exome AF: 0.0000894

Gnomad4 ASJ exome AF: 0.0000383

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000148

Gnomad4 OTH exome AF: 0.000149

GnomAD4 genome AF: 0.000479 AC: 73 AN: 152340 Hom.: 0 Cov.: 34 AF XY: 0.000483 AC XY: 36 AN XY: 74500

Gnomad4 AFR AF: 0.00125

Gnomad4 AMR AF: 0.000196

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000235

Gnomad4 OTH AF: 0.000948

Alfa AF: 0.000424 Hom.: 0

Bravo AF: 0.000427

Asia WGS AF: 0.000577 AC: 2 AN: 3478

EpiCase AF: 0.000382

EpiControl AF: 0.000533

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Benign:3

Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Jul 20, 2020	- -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Sep 07, 2017	- -
Benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Oct 01, 2022	CHRNA4: BS1, BS2 -

Autosomal dominant nocturnal frontal lobe epilepsy Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 18, 2024

- -

Inborn genetic diseases Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 06, 2016

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.49
CADD	Benign	1.3
DANN	Benign	0.90

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs113080067; hg19: chr20-61990903;