X-10185033-A-G

Variant names:

• chrX-10185033-A-G
• rs1555973635
• NM_001830.4:c.1A>G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Supporting PM2 PP5

The NM_001830.4(CLCN4):​c.1A>G​(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000922 in 1,085,185 control chromosomes in the GnomAD database, with no homozygous occurrence. There are no hemizygote samples in GnomAD. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 23)
  • Exomes 𝑓: 9.2e-7 (0 hom. 0 hem.)
• Consequence: CLCN4 NM_001830.4 start_lost
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 2.56

Genes affected

CLCN4 (HGNC:2022): (chloride voltage-gated channel 4) 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. Chloride channel 4 has an evolutionary conserved CpG island and is conserved in both mouse and hamster. This gene is mapped in close proximity to APXL (Apical protein Xenopus laevis-like) and OA1 (Ocular albinism type I), which are both located on the human X chromosome at band p22.3. The physiological role of chloride channel 4 remains unknown but may contribute to the pathogenesis of neuronal disorders. Alternate splicing results in two transcript variants that encode different proteins. [provided by RefSeq, Mar 2012]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Start lost variant, no pathogenic variants between lost start and next in-frame start position. Next in-frame start position is after 18 CDS bases. Genomic position: 10185050. Lost 0.008 part of the original CDS.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant X-10185033-A-G is Pathogenic according to our data. Variant chrX-10185033-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 489100.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CLCN4	NM_001830.4	c.1A>G	p.Met1?	start_lost	Exon 3 of 13	ENST00000380833.9	NP_001821.2
CLCN4	NM_001256944.2	c.-38-9878A>G		intron_variant	Intron 2 of 10		NP_001243873.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CLCN4	ENST00000380833.9	c.1A>G	p.Met1?	start_lost	Exon 3 of 13	1	NM_001830.4	ENSP00000370213.4

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome AF: 9.22e-7 AC: 1 AN: 1085185 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 352693

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: 0.00000120

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 23

Bravo AF: 0.0000113

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Feb 06, 2023

Initiation codon variant in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge -

Intellectual disability, X-linked 49 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Jul 17, 2023

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3B. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with Raynaud-Claes syndrome (MIM#300114). However, toxic gain of function has also been observed (PMID: 36385166). (I) 0110 - This gene is associated with X-linked dominant disease. (I) 0112 - The condition associated with this gene has incomplete penetrance, however this is exclusive to females (PMID: 27550844). (I) 0207 - Variant is predicted to result in a loss of the canonical translation initiation codon (ATG) but an alternative initiation codon is known to exist. This variant does not affect the initiation codon of alternative transcript NM_001256944, and there are several downstream, inframe initiation codons within this transcript (NCBI, UCSC). (I) 0251 - This variant is heterozygous. (I) 0302 - Variant is present in gnomAD (v2) <0.001 for a dominant condition (1 heterozygote, 0 homozygotes, 0 hemizygotes). (SP) 0705 - No comparable initiation codon variants have previous evidence for pathogenicity. (I) 0803 - This variant has limited previous evidence of pathogenicity in an unrelated individual. This variant has been reported as likely pathogenic, and was observed in a hemizygous male with autism, where the variant was inherited from his unaffected mother (ClinVar, personal communication). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1205 - This variant has been shown to be maternally inherited (by trio analysis). (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.031	T
BayesDel_noAF	Benign	-0.19
CADD	Benign	18
DANN	Benign	0.97
DEOGEN2	Benign	0.15	T;T;.
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.90	D;D;D
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Uncertain	-0.13	T
PROVEAN	Benign	-0.57	N;N;N
REVEL	Uncertain	0.34
Sift	Benign	0.083	T;T;T
Sift4G	Benign	0.40	T;T;T
Polyphen		0.0	B;.;.
Vest4		0.48
MutPred		0.99		Loss of solvent accessibility (P = 0.3103);Loss of solvent accessibility (P = 0.3103);Loss of solvent accessibility (P = 0.3103);
MVP		0.93
ClinPred		0.95	D
GERP RS		3.9
Varity_R		0.29
gMVP		0.92

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: rs1555973635; hg19: chrX-10153073;