rs547603982

Variant names:

• chr7-143332420-C-T
• rs547603982
• NM_000083.3:c.1168C>T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PP2 PP3

The NM_000083.3(CLCN1):​c.1168C>T​(p.Arg390Cys) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.0000062 in 1,613,442 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R390L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: CLCN1 NM_000083.3 missense, splice_region
• Scores: Splicing: ADA: 0.9764
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.74
• Publications: 0 publications found

Genes affected

CLCN1 (HGNC:2019): (chloride voltage-gated channel 1) The CLCN family of voltage-dependent chloride channel genes comprises nine members (CLCN1-7, Ka and Kb) which demonstrate quite diverse functional characteristics while sharing significant sequence homology. The protein encoded by this gene regulates the electric excitability of the skeletal muscle membrane. Mutations in this gene cause two forms of inherited human muscle disorders: recessive generalized myotonia congenita (Becker) and dominant myotonia (Thomsen). Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2012]

CLCN1 Gene-Disease associations (from GenCC):

• myotonia congenita, autosomal dominant

  Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• myotonia congenita, autosomal recessive

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• Thomsen and Becker disease

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 106 curated pathogenic missense variants (we use a threshold of 10). The gene has 18 curated benign missense variants. Gene score misZ: 0.21191 (below the threshold of 3.09). Trascript score misZ: 0.95247 (below the threshold of 3.09). GenCC associations: The gene is linked to myotonia congenita, autosomal dominant, myotonia congenita, autosomal recessive, Thomsen and Becker disease.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CLCN1	NM_000083.3	c.1168C>T	p.Arg390Cys	missense_variant, splice_region_variant	Exon 11 of 23	ENST00000343257.7	NP_000074.3
CLCN1	NR_046453.2	n.1273C>T		splice_region_variant, non_coding_transcript_exon_variant	Exon 11 of 22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CLCN1	ENST00000343257.7	c.1168C>T	p.Arg390Cys	missense_variant, splice_region_variant	Exon 11 of 23	1	NM_000083.3	ENSP00000339867.2
CLCN1	ENST00000432192.6	n.*453C>T		splice_region_variant, non_coding_transcript_exon_variant	Exon 11 of 23	1		ENSP00000395949.2
CLCN1	ENST00000432192.6	n.*453C>T		3_prime_UTR_variant	Exon 11 of 23	1		ENSP00000395949.2
CLCN1	ENST00000650516.2	c.1168C>T	p.Arg390Cys	missense_variant, splice_region_variant	Exon 11 of 23			ENSP00000498052.2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152102 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 251456 AF XY: 0.0000147

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461222 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 726986

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39694

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86244

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111410

Other (OTH) AF: 0.0000166 AC: 1 AN: 60370

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152220 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74442

African (AFR) AF: 0.00 AC: 0 AN: 41536

American (AMR) AF: 0.00 AC: 0 AN: 15288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5174

South Asian (SAS) AF: 0.000208 AC: 1 AN: 4818

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10604

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68014

Other (OTH) AF: 0.00 AC: 0 AN: 2110

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital myotonia, autosomal recessive form;C2936781:Congenital myotonia, autosomal dominant form Uncertain:1

Aug 30, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine with cysteine at codon 390 of the CLCN1 protein (p.Arg390Cys). The arginine residue is highly conserved and there is a large physicochemical difference between arginine and cysteine. This variant is present in population databases (rs547603982, ExAC 0.01%). This variant has not been reported in the literature in individuals affected with CLCN1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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
AlphaMissense	Uncertain	0.38
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Pathogenic	0.14
CADD	Pathogenic	33
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.92	D
Eigen	Pathogenic	0.75
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.86	D
MetaSVM	Pathogenic	0.94	D
MutationAssessor	Uncertain	2.1	M
PhyloP100		3.7
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-6.0	D
REVEL	Pathogenic	0.83
Sift	Benign	0.062	T
Sift4G	Uncertain	0.027	D
Polyphen		1.0	D
Vest4		0.71
MutPred		0.76		Loss of methylation at R390 (P = 0.0222);
MVP		0.96
MPC		0.81
ClinPred		0.90	D
GERP RS		5.3
Varity_R		0.40
gMVP		0.85
Mutation Taster		=61/39	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.98
dbscSNV1_RF	Pathogenic	0.86
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: rs547603982; hg19: chr7-143029513;