NM_000748.3:c.-55C>G

Variant names:

• chr1-154567990-C-G
• rs55799808
• NM_000748.3:c.-55C>G

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000748.3(CHRNB2):​c.-55C>G variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000759 in 1,317,804 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.6e-7 (0 hom.)
• Consequence: CHRNB2 NM_000748.3 5_prime_UTR
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.202
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• familial sleep-related hypermotor epilepsy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• autosomal dominant nocturnal frontal lobe epilepsy 3

  Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• autosomal dominant nocturnal frontal lobe epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000286391 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.78).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNB2	NM_000748.3	c.-55C>G		5_prime_UTR_variant	Exon 1 of 6	ENST00000368476.4	NP_000739.1
CHRNB2	XR_001736952.3	n.213C>G		non_coding_transcript_exon_variant	Exon 1 of 7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNB2	ENST00000368476.4	c.-55C>G		5_prime_UTR_variant	Exon 1 of 6	1	NM_000748.3	ENSP00000357461.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.59e-7 AC: 1 AN: 1317804 Hom.: 0 Cov.: 27 AF XY: 0.00 AC XY: 0 AN XY: 649358

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 26838

American (AMR) AF: 0.00 AC: 0 AN: 25982

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 22208

East Asian (EAS) AF: 0.00 AC: 0 AN: 30670

South Asian (SAS) AF: 0.00 AC: 0 AN: 70962

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 35620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4344

European-Non Finnish (NFE) AF: 9.56e-7 AC: 1 AN: 1046502

Other (OTH) AF: 0.00 AC: 0 AN: 54678

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.78
CADD	Benign	11
DANN	Benign	0.55
PhyloP100		0.20
PromoterAI		-0.095	Neutral

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: rs55799808; hg19: chr1-154540466;