17-7445128-A-G

Variant names:

• chr17-7445128-A-G
• rs1064795835
• NM_000747.3:c.1A>G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PVS1_Supporting PP5

The NM_000747.3(CHRNB1):​c.1A>G​(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000103 in 1,455,992 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000010 (0 hom.)
• Consequence: CHRNB1 NM_000747.3 start_lost
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 1.15

Genes affected

CHRNB1 (HGNC:1961): (cholinergic receptor nicotinic beta 1 subunit) The muscle acetylcholine receptor is composed of five subunits: two alpha subunits and one beta, one gamma, and one delta subunit. This gene encodes the beta subunit of the acetylcholine receptor. The acetylcholine receptor changes conformation upon acetylcholine binding leading to the opening of an ion-conducting channel across the plasma membrane. Mutations in this gene are associated with slow-channel congenital myasthenic syndrome. [provided by RefSeq, Jul 2008]

ENSG00000272884 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PVS1: Start lost variant, no pathogenic variants between lost start and next in-frame start position. Next in-frame start position is after 8 codons. Genomic position: 7445149. Lost 0.015 part of the original CDS.
• PP5: Variant 17-7445128-A-G is Pathogenic according to our data. Variant chr17-7445128-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 422524.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNB1	NM_000747.3	c.1A>G	p.Met1?	start_lost	Exon 1 of 11	ENST00000306071.7	NP_000738.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNB1	ENST00000306071.7	c.1A>G	p.Met1?	start_lost	Exon 1 of 11	1	NM_000747.3	ENSP00000304290.2
ENSG00000272884	ENST00000575331.1	n.4715A>G		non_coding_transcript_exon_variant	Exon 3 of 3	1
CHRNB1	ENST00000572857.5	c.1A>G	p.Met1?	start_lost	Exon 1 of 6	4		ENSP00000461402.1
CHRNB1	ENST00000574054.1	n.21A>G		non_coding_transcript_exon_variant	Exon 1 of 2	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.0000103 AC: 15 AN: 1455992 Hom.: 0 Cov.: 31 AF XY: 0.0000124 AC XY: 9 AN XY: 724280

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.0000126

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000625 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Feb 20, 2020

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Initiation codon variant in a gene for which loss-of-function is a known mechanism of disease; Not observed in large population cohorts (Lek et al., 2016); Has not been previously published as pathogenic or benign to our knowledge -

Congenital myasthenic syndrome 2A Uncertain:1

Aug 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects the initiator methionine of the CHRNB1 mRNA. The next in-frame methionine is located at codon 8. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CHRNB1-related conditions. ClinVar contains an entry for this variant (Variation ID: 422524). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.24
CADD	Benign	22
DANN	Benign	0.97
DEOGEN2	Benign	0.083	T;.
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.30
FATHMM_MKL	Uncertain	0.91	D
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.98	D;D
MetaSVM	Uncertain	0.071	D
PROVEAN	Benign	-0.97	N;.
REVEL	Uncertain	0.59
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		0.71	P;.
Vest4		0.78
MutPred		0.99		Loss of disorder (P = 0.0441);Loss of disorder (P = 0.0441);
MVP		0.92
ClinPred		0.94	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.90
gMVP		0.72

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

Publications

LitVar

Other links and lift over

dbSNP: rs1064795835; hg19: chr17-7348447;