7-143350432-G-C

Position:

• chr7-143350432-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The ENST00000343257.7(CLCN1):​c.2464G>C​(p.Asp822His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,868 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D822N) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CLCN1 ENST00000343257.7 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.19

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a domain CBS 2 (size 55) in uniprot entity CLCN1_HUMAN there are 7 pathogenic changes around while only 0 benign (100%) in ENST00000343257.7
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.903

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CLCN1	NM_000083.3	c.2464G>C	p.Asp822His	missense_variant	21/23	ENST00000343257.7	NP_000074.3
CLCN1	NR_046453.2	n.2419G>C		non_coding_transcript_exon_variant	20/22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CLCN1	ENST00000343257.7	c.2464G>C	p.Asp822His	missense_variant	21/23	1	NM_000083.3	ENSP00000339867	P4
CLCN1	ENST00000432192.6	c.*1749G>C		3_prime_UTR_variant, NMD_transcript_variant	21/23	1		ENSP00000395949
CLCN1	ENST00000650516.2	c.2464G>C	p.Asp822His	missense_variant	21/23			ENSP00000498052	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461868 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Athena Diagnostics

Jun 05, 2017

- -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 10, 2023

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. 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. ClinVar contains an entry for this variant (Variation ID: 447063). This variant has not been reported in the literature in individuals affected with CLCN1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces aspartic acid, which is acidic and polar, with histidine, which is basic and polar, at codon 822 of the CLCN1 protein (p.Asp822His). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.43
CADD	Pathogenic	30
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.74	D
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.24	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Uncertain	2.0	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.88
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.54		Loss of loop (P = 0.1242);
MVP		0.98
MPC		0.81
ClinPred		1.0	D
GERP RS		4.5
Varity_R		0.88
gMVP		0.86

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs143146088; hg19: chr7-143047525;