rs563864511

Positions:

• chr7-143331312-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM1

The NM_000083.3(CLCN1):​c.1060A>G​(p.Ile354Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000684 in 1,608,984 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. I354S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000069 (0 hom.)
• Consequence: CLCN1 NM_000083.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.34

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 Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a helix (size 30) in uniprot entity CLCN1_HUMAN there are 8 pathogenic changes around while only 0 benign (100%) in NM_000083.3

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CLCN1	NM_000083.3	c.1060A>G	p.Ile354Val	missense_variant	9/23	ENST00000343257.7
CLCN1	NR_046453.2	n.1165A>G		non_coding_transcript_exon_variant	9/22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CLCN1	ENST00000343257.7	c.1060A>G	p.Ile354Val	missense_variant	9/23	1	NM_000083.3	P4
CLCN1	ENST00000432192.6	c.*345A>G		3_prime_UTR_variant, NMD_transcript_variant	9/23	1
CLCN1	ENST00000650516.2	c.1060A>G	p.Ile354Val	missense_variant	9/23			A2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152142 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000193

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

GnomAD3 exomes AF: 0.0000278 AC: 7 AN: 251474 Hom.: 0 AF XY: 0.0000221 AC XY: 3 AN XY: 135908

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000381

Gnomad SAS 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: 0.00000686 AC: 10 AN: 1456724 Hom.: 0 Cov.: 31 AF XY: 0.00000690 AC XY: 5 AN XY: 725090

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000227

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.03e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152260 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74448

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 31, 2022

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 354 of the CLCN1 protein (p.Ile354Val). This variant is present in population databases (rs563864511, gnomAD 0.03%). This variant has not been reported in the literature in individuals affected with CLCN1-related conditions. ClinVar contains an entry for this variant (Variation ID: 568351). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Uncertain	0.064	T
BayesDel_noAF	Pathogenic	0.16
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.52	D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.92	D
M_CAP	Uncertain	0.15	D
MetaRNN	Uncertain	0.74	D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Uncertain	2.2	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-0.87	N
REVEL	Pathogenic	0.76
Sift	Benign	0.085	T
Sift4G	Benign	0.14	T
Polyphen		1.0	D
Vest4		0.69
MutPred		0.69		Gain of catalytic residue at I354 (P = 0.3408);
MVP		0.91
MPC		0.62
ClinPred		0.59	D
GERP RS		4.9
Varity_R		0.37
gMVP		0.66

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.090		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: rs563864511; hg19: chr7-143028405;