Renal dysplasia in Bardet-Biedl syndrome.

BACKGROUND: Bardet-Biedl syndrome (BBS) is a multisystem genetic disorder characterized with central obesity, pigmentary retinopathy, polydactyly, mental retardation, and hypogenitalism. Renal abnormalities have been recognized as a cardinal feature of the disease with serious prognostic implication. The aim of this study was to analyze the renal status in children with BBS and to implement appropriate interventions in those with progressive course Patients and methods: The diagnosis of BBS was established on the basis of criteria proposed by Beales et al. (J Med Genet 1999). Imaging of the kidneys and urinary tract was performed with ultrasound study, Tc99(m)DMSA scan and a cystographic study. Twenty four hour urine collections were obtained for estimation of proteinuria and creatinine clearance. Blood pressure was monitored at clinical visits or as 24-hour ambulatory monitoring. RESULTS: There were 4 children (2 males, 2 females). All four children displayed abnormal kidney ultrasound and Tc99(m)DMSA scan resembling dysplastic kidney(s). Two of them had overt proteinuria (glomerulo-tubular pattern). Three children had normal blood pressure and glomerular filtration rate (GFR): 107, 145 and 95 ml/min/1.73m(2), and the fourth had hypertension and progressive worsening of the GFR at 65 ml/min/1.73m(2). CONCLUSION: Children with BBS should undergo imaging studies of the kidneys and urinary tract at initial work up; in those with renal dysplasia proteinuria, GFR and blood pressure should be regularly monitored to slow down progression to terminal renal failure.

OCRL1 mutation in a boy with Dent disease, mild mental retardation, but without cataracts.

BACKGROUND: Oculocerebrorenal (Lowe) syndrome is an X-linked multisystem disease characterized by renal proximal tubulopathy, mental retardation, and congenital cataracts. We present a 19-year-old boy who was found to have low molecular weight proteinuria, hypercalciuria, mild generalized hyperaminoaciduria and intermittent microscopic hematuria at the age of 3. METHODS: Standard clinical and biochemical examinations and mutational analysis of the CLNC5 and OCRL1 gene were performed for the patient. RESULTS: The patient fulfilled diagnostic criteria for Dent disease, but lacked mutation in CLCN5. Sequencing of candidate genes revealed a mutation in his OCRL1 gene, which encodes for enzyme PIP2 5-phosphatase. The enzyme was not detected by western blot analysis, and decreased activity of the enzyme PIP2 5-phosphatase was observed in cultured skin fibroblasts. The boy had only mild mental retardation, mildly elevated muscle enzymes, but no neurological deficit or congenital cataracts, which are typical for Lowe syndrome. CONCLUSIONS: Children with Dent phenotype who lack CLCN5 mutation should be tested for OCRL1 mutation. OCRL1 mutations may present with mild clinical features and are not necessarily associated with congenital cataracts.