Muscle involvement in Dent disease 2.

Abstract

BACKGROUND: Dent disease, an X-linked recessive renal tubulopathy, is caused by

mutations in either CLCN5 (Dent disease 1) or OCRL (Dent disease 2). OCRL

mutations can also cause Lowe syndrome. In some cases it is difficult to

differentiate Dent disease 1 and 2 on the basis of clinical features only without

genetic tests. Several studies have shown differences in serum levels of muscle

enzymes between these diseases. The aim of our study was to test the validity of

these findings. METHODS: In total, 23 patients with Dent disease 1 (Group A),

five patients with Dent disease 2 (Group B) and 19 patients with Lowe syndrome

(Group C) were enrolled in our study. The serum levels of three muscle enzymes

[creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate

aminotransferase (AST)], were measured. The levels of a hepatic enzyme, alanine

aminotransferase (ALT), were also measured as a control. RESULTS: One patient in

Group B had muscle hypoplasia of both upper extremities. The serum levels of all

three muscle enzymes assayed were higher in Group B or C patients than in Group A

patients. Serum ALT levels were normal in all three groups of patients.

CONCLUSIONS: The serum levels of muscle enzymes in patients with Dent disease can

be used as a biomarker to predict genotypes, even though the patients do not have

clinical symptoms of muscle involvement.