rs1424224517

Positions:

• chr7-143345590-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000083.3(CLCN1):​c.2000C>T​(p.Pro667Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000286 in 1,399,646 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000029 (0 hom.)
• Consequence: CLCN1 NM_000083.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.88

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CLCN1	NM_000083.3	c.2000C>T	p.Pro667Leu	missense_variant	17/23	ENST00000343257.7	NP_000074.3
CLCN1	NR_046453.2	n.1955C>T		non_coding_transcript_exon_variant	16/22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CLCN1	ENST00000343257.7	c.2000C>T	p.Pro667Leu	missense_variant	17/23	1	NM_000083.3	ENSP00000339867.2
CLCN1	ENST00000432192.6	n.*1285C>T		non_coding_transcript_exon_variant	17/23	1		ENSP00000395949.2
CLCN1	ENST00000432192.6	n.*1285C>T		3_prime_UTR_variant	17/23	1		ENSP00000395949.2
CLCN1	ENST00000650516.2	c.2000C>T	p.Pro667Leu	missense_variant	17/23			ENSP00000498052.2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.0000127 AC: 2 AN: 157432 Hom.: 0 AF XY: 0.0000240 AC XY: 2 AN XY: 83224

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000402

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000225

GnomAD4 exome AF: 0.00000286 AC: 4 AN: 1399646 Hom.: 0 Cov.: 33 AF XY: 0.00000579 AC XY: 4 AN XY: 690452

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000558

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: 9.26e-7

Gnomad4 OTH exome AF: 0.0000172

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000378

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

Labcorp Genetics (formerly Invitae), Labcorp

Feb 03, 2022

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 667 of the CLCN1 protein (p.Pro667Leu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. 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: 531752). 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 not 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.057	T
BayesDel_noAF	Benign	-0.32
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.44	T
Eigen	Benign	-0.018
Eigen_PC	Benign	0.0075
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.87	D
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.22	T
MetaSVM	Uncertain	-0.21	T
MutationAssessor	Uncertain	2.2	M
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.0	D
REVEL	Benign	0.21
Sift	Benign	0.11	T
Sift4G	Benign	0.48	T
Polyphen		0.48	P
Vest4		0.23
MutPred		0.46		Gain of MoRF binding (P = 0.0522);
MVP		0.87
MPC		0.29
ClinPred		0.97	D
GERP RS		5.3
Varity_R		0.16
gMVP		0.54

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.35		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.35		Position offset: 10

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

Publications

LitVar

Other links and lift over

dbSNP: rs1424224517; hg19: chr7-143042683;