chr1-154572164-G-T

Variant names:

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BS2

The NM_000748.3(CHRNB2):c.1338+3G>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000521 in 1,536,830 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000043 ( 0 hom. )

Consequence

CHRNB2
NM_000748.3 splice_region, intron

Scores

Splicing: ADA: 0.9995

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 0.768

Variant links:

Genes affected

CHRNB2 (HGNC:1962): (cholinergic receptor nicotinic beta 2 subunit) Neuronal acetylcholine receptors are homo- or heteropentameric complexes composed of homologous alpha and beta subunits. They belong to a superfamily of ligand-gated ion channels which allow the flow of sodium and potassium across the plasma membrane in response to ligands such as acetylcholine and nicotine. This gene encodes one of several beta subunits. Mutations in this gene are associated with autosomal dominant nocturnal frontal lobe epilepsy. [provided by RefSeq, Jul 2008]

CHRNB2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -4 ACMG points.

BS2

High AC in GnomAdExome4 at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein	UniProt
CHRNB2	NM_000748.3 link	c.1338+3G>T	splice_region_variant, intron_variant	Intron 5 of 5	ENST00000368476.4	NP_000739.1	P17787Q5SXY3
CHRNB2	XM_017000180.3 link	c.828+3G>T	splice_region_variant, intron_variant	Intron 2 of 2		XP_016855669.1
CHRNB2	XR_001736952.3 link	n.1605+3G>T	splice_region_variant, intron_variant	Intron 5 of 6

Ensembl

Gene	Transcript	HGVSc	Effect	Exon rank	TSL	MANE	Protein	UniProt
CHRNB2	ENST00000368476.4 link	c.1338+3G>T	splice_region_variant, intron_variant	Intron 5 of 5	1	NM_000748.3	ENSP00000357461.3	P17787
CHRNB2	ENST00000637900.1 link	c.1344+3G>T	splice_region_variant, intron_variant	Intron 5 of 5	5		ENSP00000490474.1	A0A1B0GVD7
CHRNB2	ENST00000636034.1 link	n.1338+3G>T	splice_region_variant, intron_variant	Intron 5 of 8	5		ENSP00000489703.1	A0A1B0GTH5

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152256

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

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:

0.0000151

AC:

AN:

132374

Hom.:

AF XY:

0.00

AC XY:

AN XY:

72214

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000819

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000433

AC:

AN:

1384574

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

683344

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000168

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:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152256

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74384

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.000131

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:

0.0000340

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy 3

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Oct 31, 2018

- -

Autosomal dominant nocturnal frontal lobe epilepsy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 31, 2024

This sequence change falls in intron 5 of the CHRNB2 gene. It does not directly change the encoded amino acid sequence of the CHRNB2 protein. It affects a nucleotide within the consensus splice site. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with CHRNB2-related conditions. ClinVar contains an entry for this variant (Variation ID: 430409). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 29, 2020

The c.1338+3G>T intronic alteration consists of a G to T substitution 3 nucleotides after exon 5 (coding exon 5) of the CHRNB2 gene. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 19, 2017

A variant of uncertain significance has been identified in the CHRNB2 gene. The c.1338+3 G>T variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The c.1338+3 G>T variant is not observed in large population cohorts; however, limited data are available (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). Several in-silico splice prediction models predict that c.1338+3 G>T may damage or destroy the natural splice donor site in intron 5 and lead to abnormal gene splicing. However, in the absence of RNA/functional studies, the actual effect of this sequence change in this individual is unknown. Additionally, to our knowledge, splice variants have not been reported in the CHRNB2 gene (Stenson et al., 2014). Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.43

CADD

Benign

DANN

Benign

0.82

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.73

SpliceAI score (max)

0.69

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.69

Position offset: -3

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over