Novel OCRL mutations in patients with Dent-2 disease

Area of Science:

• Nephrology
• Genetics
• Molecular Biology

Background:

• Dent disease is an X-linked tubulopathy primarily linked to CLCN5 gene mutations.
• Approximately 15% of Dent disease patients have OCRL gene mutations, leading to Dent-2 disease, distinct from Lowe syndrome.
• Distinguishing Dent-2 from Lowe syndrome is crucial due to differing severities.

Purpose of the Study:

• Investigate OCRL gene defects in CLCN5-negative patients with Dent disease phenotype.
• Characterize the clinical and genetic spectrum of Dent-2 disease.
• Clarify the distinction between Dent-2 disease and Lowe syndrome.

Main Methods:

• Studied 14 CLCN5-negative patients from 12 families presenting with Dent disease-like symptoms.
• Performed genetic analysis to identify mutations in the OCRL gene.
• Compared renal and extra-renal phenotypes with CLCN5-mutated Dent disease and Lowe syndrome.

Main Results:

• Identified six families with OCRL gene mutations (three novel, three recurrent) in CLCN5-negative patients.
• Observed a renal phenotype in OCRL-mutated patients largely identical to CLCN5-mutated Dent disease, with less nephrocalcinosis.
• Noted overlapping extra-renal symptoms with Lowe syndrome, including cataracts and developmental impairment.

Conclusions:

• OCRL gene mutations are a significant cause of Dent disease phenotype in CLCN5-negative individuals.
• The phenotypic overlap between Dent-2 disease and Lowe syndrome necessitates careful genetic and clinical evaluation.
• Genetic testing for OCRL mutations is essential for accurate diagnosis and management of Dent disease spectrum disorders.