NM_000083.3:c.1205C>T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PP2PP3BP4_StrongBP6

The NM_000083.3(CLCN1):c.1205C>T(p.Ala402Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000075 in 1,614,076 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. A402A) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00011 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000071 ( 0 hom. )

Consequence

CLCN1
NM_000083.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4B:2

Conservation

PhyloP100: 7.56

Publications

10 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: Likely_benign. The variant received -3 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

Multiple lines of computational evidence support a deleterious effect 7: BayesDel_noAF, Cadd, Dann, Eigen, phyloP100way_vertebrate, REVEL, REVEL [when max_spliceai, FATHMM_MKL, MetaRNN, MutationTaster was below the threshold]

BP4

Computational evidence support a benign effect (MetaRNN=0.04256195).

BP6

Variant 7-143332457-C-T is Benign according to our data. Variant chr7-143332457-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 359107.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CLCN1	NM_000083.3 link	c.1205C>T	p.Ala402Val	missense_variant	Exon 11 of 23	ENST00000343257.7	NP_000074.3	P35523
CLCN1	NR_046453.2 link	n.1310C>T		non_coding_transcript_exon_variant	Exon 11 of 22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
CLCN1	ENST00000343257.7 link	c.1205C>T	p.Ala402Val	missense_variant	Exon 11 of 23	1	NM_000083.3	ENSP00000339867.2	P35523
CLCN1	ENST00000432192.6 link	n.*490C>T		non_coding_transcript_exon_variant	Exon 11 of 23	1		ENSP00000395949.2	H7C0N6
CLCN1	ENST00000432192.6 link	n.*490C>T		3_prime_UTR_variant	Exon 11 of 23	1		ENSP00000395949.2	H7C0N6
CLCN1	ENST00000650516.2 link	c.1205C>T	p.Ala402Val	missense_variant	Exon 11 of 23			ENSP00000498052.2	A0A3B3IU72

Frequencies

GnomAD3 genomes

AF:

0.000112

AC:

AN:

152110

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00328

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

GnomAD2 exomes

AF:

0.000350

AC:

AN:

251476

AF XY:

0.000316

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00473

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000711

AC:

104

AN:

1461848

Hom.:

Cov.:

AF XY:

0.0000743

AC XY:

AN XY:

727222

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00224

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111970

Other (OTH)

AF:

0.000182

AC:

AN:

60392

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.468

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:

0.000112

AC:

AN:

152228

Hom.:

Cov.:

AF XY:

0.000121

AC XY:

AN XY:

74422

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41530

American (AMR)

AF:

0.00

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00329

AC:

AN:

5174

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10602

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68020

Other (OTH)

AF:

0.00

AC:

AN:

2108

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.534

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:

0.0000429

Hom.:

Bravo

AF:

0.000110

ExAC

AF:

0.000305

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4Benign:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Jun 08, 2016

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The A402V variant was previously reported in a patient with possible myotonia congenita (Fialho et al., 2007), and in two patients with a presumptive diagnosis of paroxysmal kinesigenic dyskinesia (Wang et al., 2016), however, functional studies were not completed in either publication. The A402V variant was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project; however, A402V was reported in the 1000 Genomes Project in 3/1008 (0.3%) alleles from individuals of East Asian background. The A402V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. However, this substitution occurs at a position that is conserved in mammals, and missense variants in nearby residues (T398I; P408A) have been reported in the Human Gene Mutation Database in association with myotonia congenita (Stenson et al., 2014). In silico analysis predicts this variant is probably damaging to the protein structure/function. -

Aug 02, 2019

Athena Diagnostics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

May 06, 2021

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

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

Uncertain:1Benign:1

Juno Genomics, Hangzhou Juno Genomics, Inc

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

PP3_Moderate+PM3_Strong+PS4_Supporting+BS2 -

Oct 19, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Batten-Turner congenital myopathy

Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.47

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Pathogenic

0.41

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.78

Eigen

Pathogenic

0.83

Eigen_PC

Pathogenic

0.81

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.99

M_CAP

Uncertain

0.24

MetaRNN

Benign

0.043

MetaSVM

Pathogenic

0.95

MutationAssessor

Uncertain

2.5

PhyloP100

7.6

PrimateAI

Uncertain

0.64

PROVEAN

Uncertain

-3.0

REVEL

Pathogenic

0.92

Sift

Uncertain

0.0060

Sift4G

Uncertain

0.0070

Polyphen

1.0

Vest4

0.69

MVP

0.99

MPC

0.73

ClinPred

0.21

GERP RS

5.4

Varity_R

0.82

gMVP

0.86

Mutation Taster

=16/84

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.12

Details are displayed if max score is > 0.2

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