Muscle involvement in Dent disease 2.

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.