rs1423567292

chr7-143323307-AG-A

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PVS1_Moderate PM2 PP3 PP5_Very_Strong

The NM_000083.3(CLCN1):c.698del variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000025 in 1,597,684 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CLCN1 NM_000083.3 splice_acceptor
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 10.0

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 Pathogenic. Variant got 13 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.02595214 fraction of the gene. Cryptic splice site detected, with MaxEntScore 9.7, offset of 0 (no position change), new splice context is: cctcgctccccctctcccAGgcc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: No computational evidence supports a deleterious effect, but strongly conserved according to phyloP
• PP5: Variant 7-143323307-AG-A is Pathogenic according to our data. Variant chr7-143323307-AG-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 447069.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CLCN1	NM_000083.3	c.698del		splice_acceptor_variant		ENST00000343257.7
CLCN1	NR_046453.2	n.800del		splice_acceptor_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CLCN1	ENST00000343257.7	c.698del		splice_acceptor_variant		1	NM_000083.3	P4

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 150948 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000487

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: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250814 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135596

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 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: 0.00000138 AC: 2 AN: 1446736 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 720698

Gnomad4 AFR exome AF: 0.0000603

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 150948 Hom.: 0 Cov.: 32 AF XY: 0.0000272 AC XY: 2 AN XY: 73660

Gnomad4 AFR AF: 0.0000487

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Athena Diagnostics

Oct 28, 2016

- -

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

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Jun 23, 2023

For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. ClinVar contains an entry for this variant (Variation ID: 447069). This premature translational stop signal has been observed in individual(s) with CLCN1-related condition (Invitae). This variant is present in population databases (no rsID available, gnomAD 0.008%). This sequence change creates a premature translational stop signal (p.Gly233Alafs*35) in the CLCN1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CLCN1 are known to be pathogenic (PMID: 17932099, 22094069, 23739125). -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.84		Position offset: 3
DS_AL_spliceai		0.93		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1423567292; hg19: chr7-143020400;