rs762754992

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1PM2PM5PP2PP3_StrongPP5_Very_Strong

The NM_000083.3(CLCN1):​c.1649C>G​(p.Thr550Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T550M) has been classified as Pathogenic.

Frequency

Genomes: not found (cov: 32)
Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

CLCN1
NM_000083.3 missense

Scores

17
1
1

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3

Conservation

PhyloP100: 7.90

Publications

11 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

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 19 ACMG points.

PM1
In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_000083.3
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr7-143341995-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 208084.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
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
MetaRNN computational evidence supports a deleterious effect, 0.98
PP5
Variant 7-143341995-C-G is Pathogenic according to our data. Variant chr7-143341995-C-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 1013567.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
CLCN1NM_000083.3 linkc.1649C>G p.Thr550Arg missense_variant Exon 15 of 23 ENST00000343257.7 NP_000074.3 P35523
CLCN1NR_046453.2 linkn.1604C>G non_coding_transcript_exon_variant Exon 14 of 22

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
CLCN1ENST00000343257.7 linkc.1649C>G p.Thr550Arg missense_variant Exon 15 of 23 1 NM_000083.3 ENSP00000339867.2 P35523
CLCN1ENST00000432192.6 linkn.*934C>G non_coding_transcript_exon_variant Exon 15 of 23 1 ENSP00000395949.2 H7C0N6
CLCN1ENST00000432192.6 linkn.*934C>G 3_prime_UTR_variant Exon 15 of 23 1 ENSP00000395949.2 H7C0N6
CLCN1ENST00000650516.2 linkc.1649C>G p.Thr550Arg missense_variant Exon 15 of 23 ENSP00000498052.2 A0A3B3IU72

Frequencies

GnomAD3 genomes
Cov.:
32
GnomAD4 exome
AF:
6.84e-7
AC:
1
AN:
1461876
Hom.:
0
Cov.:
33
AF XY:
0.00000138
AC XY:
1
AN XY:
727242
show subpopulations
African (AFR)
AF:
0.00
AC:
0
AN:
33480
American (AMR)
AF:
0.00
AC:
0
AN:
44724
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26136
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39700
South Asian (SAS)
AF:
0.00
AC:
0
AN:
86256
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53416
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5764
European-Non Finnish (NFE)
AF:
8.99e-7
AC:
1
AN:
1112004
Other (OTH)
AF:
0.00
AC:
0
AN:
60396
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.475
Heterozygous variant carriers
0
0
1
1
2
2
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance
GnomAD4 genome
Cov.:
32
Alfa
AF:
0.00
Hom.:
0

ClinVar

Significance: Pathogenic/Likely pathogenic
Submissions summary: Pathogenic:3
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

not provided Pathogenic:1
Mar 01, 2022
CeGaT Center for Human Genetics Tuebingen
Significance:Pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

CLCN1: PM3:Strong, PM2, PM5, PP3, PP4 -

Congenital myotonia, autosomal recessive form;C2936781:Congenital myotonia, autosomal dominant form Pathogenic:1
Jan 09, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Likely pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with arginine, which is basic and polar, at codon 550 of the CLCN1 protein (p.Thr550Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with autosomal recessive myotonia congenita (PMID: 21221019, 33263785). ClinVar contains an entry for this variant (Variation ID: 1013567). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt CLCN1 protein function with a positive predictive value of 95%. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Congenital myotonia, autosomal recessive form Pathogenic:1
Feb 20, 2024
Laboratory of Medical Genetics, National & Kapodistrian University of Athens
Significance:Pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Pathogenic
1.0
BayesDel_addAF
Pathogenic
0.55
D
BayesDel_noAF
Pathogenic
0.56
CADD
Pathogenic
32
DANN
Uncertain
1.0
DEOGEN2
Pathogenic
0.97
D
Eigen
Pathogenic
1.1
Eigen_PC
Pathogenic
1.0
FATHMM_MKL
Pathogenic
0.99
D
LIST_S2
Pathogenic
1.0
D
M_CAP
Pathogenic
0.60
D
MetaRNN
Pathogenic
0.98
D
MetaSVM
Pathogenic
1.1
D
MutationAssessor
Pathogenic
4.4
H
PhyloP100
7.9
PrimateAI
Pathogenic
0.90
D
PROVEAN
Pathogenic
-5.3
D
REVEL
Pathogenic
0.98
Sift
Pathogenic
0.0
D
Sift4G
Pathogenic
0.0010
D
Polyphen
1.0
D
Vest4
0.97
MutPred
0.86
Gain of methylation at T550 (P = 0.0432);
MVP
0.99
MPC
0.79
ClinPred
1.0
D
GERP RS
5.9
Varity_R
0.98
gMVP
0.99
Mutation Taster
=8/92
disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs762754992; hg19: chr7-143039088; API