chr20-63356425-C-A

Position:

• chr20-63356425-C-A

Variant summary

Our verdict is Benign. Variant got -13 ACMG points: 0P and 13B. BP4_Strong BP6 BS1 BS2

The NM_000744.7(CHRNA4):​c.229-10G>T variant causes a splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000213 in 1,599,380 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000086 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000015 (0 hom.)
• Consequence: CHRNA4 NM_000744.7 splice_polypyrimidine_tract, intron
• Scores: Splicing: ADA: 0.00001679
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: -0.428

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 -13 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.85).
• BP6: Variant 20-63356425-C-A is Benign according to our data. Variant chr20-63356425-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 593527.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.
• BS1: Variant frequency is greater than expected in population amr. gnomad4 allele frequency = 0.0000855 (13/152010) while in subpopulation AMR AF= 0.000851 (13/15276). AF 95% confidence interval is 0.000503. There are 0 homozygotes in gnomad4. There are 10 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High AC in GnomAd4 at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNA4	NM_000744.7	c.229-10G>T		splice_polypyrimidine_tract_variant, intron_variant		ENST00000370263.9	NP_000735.1
CHRNA4	NM_001256573.2	c.-318-10G>T		splice_polypyrimidine_tract_variant, intron_variant			NP_001243502.1
CHRNA4	NR_046317.2	n.413-10G>T		splice_polypyrimidine_tract_variant, intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHRNA4	ENST00000370263.9	c.229-10G>T		splice_polypyrimidine_tract_variant, intron_variant		1	NM_000744.7	ENSP00000359285	P1

Frequencies

GnomAD3 genomes AF: 0.0000855 AC: 13 AN: 152010 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000851

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: 0.00

GnomAD3 exomes AF: 0.0000447 AC: 10 AN: 223806 Hom.: 0 AF XY: 0.0000414 AC XY: 5 AN XY: 120650

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000277

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: 0.0000101

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000145 AC: 21 AN: 1447370 Hom.: 0 Cov.: 32 AF XY: 0.0000125 AC XY: 9 AN XY: 718354

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000300

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000543

Gnomad4 OTH exome AF: 0.0000334

GnomAD4 genome AF: 0.0000855 AC: 13 AN: 152010 Hom.: 0 Cov.: 32 AF XY: 0.000135 AC XY: 10 AN XY: 74232

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.000851

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000793

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Aug 17, 2017

- -

Autosomal dominant nocturnal frontal lobe epilepsy Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 20, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.85
CADD	Benign	0.66
DANN	Benign	0.58

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000017
dbscSNV1_RF	Benign	0.0020
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

Publications

LitVar

Other links and lift over

dbSNP: rs776781462; hg19: chr20-61987777;