Genetic Variant CLCN1:p.Gly285Glu (chr7-143330772-G-A) – ACMG Classification: Pathogenic (18 pts)

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PS3PM1PM5PP2PP3PP5_Very_Strong

The NM_000083.3(CLCN1):c.854G>A(p.Gly285Glu) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000103 in 1,614,132 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 15/24 in silico tools predict a damaging outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000329930: Published functional studies demonstrate that the G285E variant leads to absent expression of chloride currents (Kubisch et al., 1998)" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G285V) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00011 ( 0 hom. )

Consequence

CLCN1
NM_000083.3 missense, splice_region

Scores

Splicing: ADA: 0.9909

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:13

Conservation

PhyloP100: 9.99

Publications

20 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 18 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000329930: Published functional studies demonstrate that the G285E variant leads to absent expression of chloride currents (Kubisch et al., 1998); PMID: 15162127; SCV000612800: Assessment of experimental evidence suggests this variant results in abnormal protein function. (PMID: 9736777); SCV000636300: Experimental studies have shown that this missense change affects CLCN1 function (PMID: 9736777).; SCV002506923: Functional studies demonstrate the p.Gly285Glu variant leads to absence of chloride currents [PMID:9736777].; SCV004115388: Functional studies on this variant have demonstrated that it affects chloride channel function (Kubisch et al. 1998. PubMed ID: 9736777).

PM1

In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 uncertain in NM_000083.3

PM5

Other missense variant is known to change same aminoacid residue: Variant chr7-143330772-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2083486.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

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

PP5

Variant 7-143330772-G-A is Pathogenic according to our data. Variant chr7-143330772-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 280100.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000083.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CLCN1	NM_000083.3	MANE Select	c.854G>A	p.Gly285Glu	missense splice_region	Exon 8 of 23	NP_000074.3	P35523
	CLCN1	NR_046453.2		n.959G>A		splice_region non_coding_transcript_exon	Exon 8 of 22

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
CLCN1	ENST00000343257.7	TSL:1 MANE Select	c.854G>A	p.Gly285Glu	missense splice_region	Exon 8 of 23	ENSP00000339867.2	P35523
CLCN1	ENST00000432192.6	TSL:1	n.*139G>A		splice_region non_coding_transcript_exon	Exon 8 of 23	ENSP00000395949.2	H7C0N6
CLCN1	ENST00000455478.6	TSL:1	n.*139G>A		splice_region non_coding_transcript_exon	Exon 7 of 7	ENSP00000400027.2	H7C1F4

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152208

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:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000588

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000557

AC:

AN:

251352

AF XY:

0.0000589

show subpopulations

Gnomad AFR exome

AF:

0.0000615

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:

0.000114

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000111

AC:

162

AN:

1461806

Hom.:

Cov.:

AF XY:

0.0000921

AC XY:

AN XY:

727190

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33476

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53410

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5728

European-Non Finnish (NFE)

AF:

0.000144

AC:

160

AN:

1111990

Other (OTH)

AF:

0.0000166

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.486

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:

0.0000328

AC:

AN:

152326

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74484

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41572

American (AMR)

AF:

0.00

AC:

AN:

15304

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5176

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10618

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000588

AC:

AN:

68036

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.515

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:

0.0000837

Hom.:

Bravo

AF:

0.0000491

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000233

AC:

ExAC

AF:

0.0000576

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.0000545

EpiControl

AF:

0.000296

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

not provided (7)

Congenital myotonia, autosomal recessive form;C2936781:Congenital myotonia, autosomal dominant form (3)

CLCN1-related disorder (1)

Smith-Lemli-Opitz syndrome (1)

Tip-toe gait (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Pathogenic

0.39

BayesDel_noAF

Pathogenic

0.56

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.96

Eigen

Pathogenic

0.84

Eigen_PC

Pathogenic

0.67

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

1.0

M_CAP

Pathogenic

0.62

MetaRNN

Pathogenic

0.96

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

4.5

PhyloP100

PrimateAI

Pathogenic

0.92

PROVEAN

Pathogenic

-7.3

REVEL

Pathogenic

0.93

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0010

Polyphen

0.99

Vest4

0.99

MVP

0.99

MPC

0.84

ClinPred

0.94

GERP RS

4.6

Varity_R

0.95

gMVP

0.98

Mutation Taster

=4/96

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

0.99

dbscSNV1_RF

Pathogenic

0.79

SpliceAI score (max)

0.19

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over