7-143351900-G-C

Position:

• chr7-143351900-G-C

Variant summary

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

The NM_000083.3(CLCN1):​c.2902G>C​(p.Asp968His) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,684 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CLCN1 NM_000083.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.41

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.2902G>C	p.Asp968His	missense_variant	23/23	ENST00000343257.7	NP_000074.3
CLCN1	NR_046453.2	n.2857G>C		non_coding_transcript_exon_variant	22/22

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CLCN1	ENST00000343257.7	c.2902G>C	p.Asp968His	missense_variant	23/23	1	NM_000083.3	ENSP00000339867.2
CLCN1	ENST00000650516.2	c.2902G>C	p.Asp968His	missense_variant	23/23			ENSP00000498052.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461684 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727128

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

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 26, 2019

This sequence change replaces aspartic acid with histidine at codon 968 of the CLCN1 protein (p.Asp968His). The aspartic acid residue is moderately conserved and there is a moderate physicochemical difference between aspartic acid and histidine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with CLCN1-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	0.18
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Benign	-0.13
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Benign	0.15	T
Eigen	Uncertain	0.62
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.83	T
M_CAP	Uncertain	0.17	D
MetaRNN	Uncertain	0.64	D
MetaSVM	Uncertain	0.74	D
MutationAssessor	Uncertain	2.3	M
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-1.9	N
REVEL	Uncertain	0.42
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.017	D
Polyphen		1.0	D
Vest4		0.56
MutPred		0.23		Loss of loop (P = 0.0804);
MVP		0.96
MPC		0.81
ClinPred		0.99	D
GERP RS		4.5
Varity_R		0.20
gMVP		0.50

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

Publications

LitVar

Other links and lift over

dbSNP: rs748630375; hg19: chr7-143048993;