NM_000083.3:c.1129C>T

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1PP5_Very_Strong

The NM_000083.3(CLCN1):c.1129C>T(p.Arg377*) variant causes a stop gained change. The variant allele was found at a frequency of 0.0000136 in 1,614,040 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 Pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. R377R) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000013 ( 0 hom. )

Consequence

CLCN1
NM_000083.3 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:6

Conservation

PhyloP100: 4.76

Publications

9 publications found

Variant links:

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

CLCN1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 16 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PP5

Variant 7-143331615-C-T is Pathogenic according to our data. Variant chr7-143331615-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 447045.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CLCN1	NM_000083.3 link	c.1129C>T	p.Arg377*	stop_gained	Exon 10 of 23	ENST00000343257.7	NP_000074.3
CLCN1	NR_046453.2 link	n.1234C>T		non_coding_transcript_exon_variant	Exon 10 of 22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein
CLCN1	ENST00000343257.7 link	c.1129C>T	p.Arg377*	stop_gained	Exon 10 of 23	1	NM_000083.3	ENSP00000339867.2
CLCN1	ENST00000432192.6 link	n.*414C>T		non_coding_transcript_exon_variant	Exon 10 of 23	1		ENSP00000395949.2
CLCN1	ENST00000432192.6 link	n.*414C>T		3_prime_UTR_variant	Exon 10 of 23	1		ENSP00000395949.2
CLCN1	ENST00000650516.2 link	c.1129C>T	p.Arg377*	stop_gained	Exon 10 of 23			ENSP00000498052.2

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152154

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.0000943

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.0000119

AC:

AN:

251462

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.000185

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000130

AC:

AN:

1461768

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

727190

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33474

American (AMR)

AF:

0.0000894

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26130

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39698

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00000899

AC:

AN:

1111918

Other (OTH)

AF:

0.0000331

AC:

AN:

60388

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.462

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152272

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74456

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41550

American (AMR)

AF:

0.00

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5174

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.0000943

AC:

AN:

10608

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68030

Other (OTH)

AF:

0.000473

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.492

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000183

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.0000165

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Pathogenic:3

Aug 02, 2019

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Oct 31, 2016

Athena Diagnostics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 10, 2023

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Reported in association with autosomal recessive myotonia congenita in the published literature (PMID: 28325641, 17932099); Nonsense variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 31589614, 34938096, 32721234, 17932099, 23893571, 25525159, 31069529, 34529042, 28325641) -

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

Pathogenic:2

May 15, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Mar 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Arg377*) in the CLCN1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CLCN1 are known to be pathogenic (PMID: 17932099, 22094069, 23739125). This variant is present in population databases (rs201714423, gnomAD 0.004%). This premature translational stop signal has been observed in individual(s) with autosomal recessive myotonia congenita (PMID: 21221019). ClinVar contains an entry for this variant (Variation ID: 447045). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

CLCN1-related disorder

Pathogenic:1

Nov 16, 2023

PreventionGenetics, part of Exact Sciences

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

The CLCN1 c.1129C>T variant is predicted to result in premature protein termination (p.Arg377*). This variant has been reported in the homozygous or compound heterozygous states in three patients with myotonia congenita (Fialho et al 2007. PubMed ID: 17932099; Modoni et al 2011. PubMed ID: 21221019), and in one patient with myotonia congenita in which a second potentially pathogenic variant was not identified (Sun et al 2020. PubMed ID: 31567646). This variant is reported in 0.012% of alleles in individuals of African descent in gnomAD (http://gnomad.broadinstitute.org/variant/7-143028708-C-T). Nonsense variants in CLCN1 are expected to be pathogenic. This variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.50

BayesDel_noAF

Pathogenic

0.53

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

0.85

Eigen_PC

Pathogenic

0.72

FATHMM_MKL

Uncertain

0.85

PhyloP100

4.8

Vest4

0.95

GERP RS

5.1

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.22

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.22

Position offset: 37

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over