NM_000083.3:c.2578G>T

Variant names:

• chr7-143350637-G-T
• rs767209392
• NM_000083.3:c.2578G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1 PM2 PP2 PP3_Moderate

The NM_000083.3(CLCN1):​c.2578G>T​(p.Val860Phe) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,642 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V860I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CLCN1 NM_000083.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 6.28
• Publications: 0 publications found

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

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM1: In a domain CBS 2 (size 55) in uniprot entity CLCN1_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000083.3
• PM2: Very rare variant in population databases, with high coverage
• 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: MetaRNN computational evidence supports a deleterious effect, 0.938

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CLCN1	NM_000083.3	MANE Select	c.2578G>T	p.Val860Phe	missense	Exon 22 of 23	NP_000074.3
	CLCN1	NR_046453.2		n.2533G>T		non_coding_transcript_exon	Exon 21 of 22

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CLCN1	ENST00000343257.7	TSL:1 MANE Select	c.2578G>T	p.Val860Phe	missense	Exon 22 of 23	ENSP00000339867.2
	CLCN1	ENST00000432192.6	TSL:1	n.*1863G>T		non_coding_transcript_exon	Exon 22 of 23	ENSP00000395949.2
	CLCN1	ENST00000432192.6	TSL:1	n.*1863G>T		3_prime_UTR	Exon 22 of 23	ENSP00000395949.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461642 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727140

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111796

Other (OTH) AF: 0.00 AC: 0 AN: 60386

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.52
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	30
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.53	D
Eigen	Pathogenic	0.79
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.25	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	0.83	D
MutationAssessor	Benign	1.6	L
PhyloP100		6.3
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-4.1	D
REVEL	Pathogenic	0.86
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.90
MutPred		0.70		Loss of catalytic residue at V860 (P = 0.1039)
MVP		0.97
MPC		0.84
ClinPred		1.0	D
GERP RS		4.2
Varity_R		0.77
gMVP		0.90
Mutation Taster		=8/92	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs767209392; hg19: chr7-143047730; COSMIC: COSV58374909; COSMIC: COSV58374909;