Mutational analysis of CLC-5, cofilin and CLC-4 in patients with Dent's disease.
OBJECTIVE
Dent's disease is caused by mutations in the chloride/proton antiporter, CLC-5, or oculo-cerebro-renal-syndrome-of-Lowe (OCRL1) genes.


METHODS
Eighteen probands with Dent's disease were investigated for mutations in CLC-5 and two of its interacting proteins, CLC-4 and cofilin. Wild-type and mutant CLC-5s were assessed in kidney cells. Urinary calcium excretion following an oral calcium challenge was studied in one family.


RESULTS
Seven different CLC-5 mutations consisting of two nonsense mutations (Arg347Stop and Arg718Stop), two missense mutations (Ser244Leu and Arg516Trp), one intron 3 donor splice site mutation, one deletion-insertion (nt930delTCinsA) and an in-frame deletion (523delVal) were identified in 8 patients. In the remaining 10 patients, DNA sequence abnormalities were not detected in the coding regions of CLC-4 or cofilin, and were independently excluded for OCRL1. Patients with CLC-5 mutations were phenotypically similar to those without. The donor splice site CLC-5 mutation resulted in exon 3 skipping. Electrophysiology demonstrated that the 523delVal CLC-5 mutation abolished CLC-5-mediated chloride conductance. Sixty percent of women with the CLC-5 deletion-insertion had nephrolithiasis, although calcium excretion before and after oral calcium challenge was similar to that in unaffected females.


CONCLUSIONS
Three novel CLC-5 mutations were identified, and mutations in OCRL1, CLC-4 and cofilin excluded in causing Dent's disease in this patient cohort.
Wu
Fiona
F
Nuffield Department of Clinical Medicine, Academic Endocrine Unit, University of Oxford, and Churchill Hospital, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK.
Reed
Anita A C
AA
Williams
Sian E
SE
Loh
Nellie Y
NY
Lippiat
Jonathan D
JD
Christie
Paul T
PT
Large
Oliver
O
Bettinelli
Alberto
A
Dillon
Michael J
MJ
Goldraich
Noemia P
NP
Hoppe
Bernd
B
Lhotta
Karl
K
Loirat
Chantal
C
Malik
Rayaz
R
Morel
Delphine
D
Kotanko
Peter
P
Roussel
Bernard
B
Rubinger
Dvora
D
Schrander-Stumpel
Connie
C
Serdaroglu
Erkin
E
Nesbit
M Andrew
MA
Ashcroft
Frances
F
Thakker
Rajesh V
RV
D000595:Amino Acid Sequence; D001483:Base Sequence; D002118:Calcium / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000652:urine; D002460:Cell Line; D018118:Chloride Channels / Q000235:genetics* / Q000502:physiology; D018389:Codon, Nonsense; D051338:Cofilin 1 / Q000235:genetics*; D004252:DNA Mutational Analysis; D004594:Electrophysiology; D005260:Female; D040181:Genetic Diseases, X-Linked / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D007674:Kidney Diseases / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D016254:Mutagenesis, Insertional; D009154:Mutation; D020125:Mutation, Missense; D010375:Pedigree; D017384:Sequence Deletion; D014162:Transfection
C495810:CFL1 protein, human; C097503:CLC-5 chloride channel; C484312:CLCN4 protein, human; D018118:Chloride Channels; D018389:Codon, Nonsense; D051338:Cofilin 1; D002118:Calcium