LAUSR

1. What is your most likely diagnosis for this patient? Medullary nephrocalcinosis can be seen due to a variety of conditions. Hypercalcemic hypercalciuria with atypical facial appearance and supravalvular aortic stenosis led us the presumptive diagnosis of Williams-Beuren Syndrome (WBS). 2. Which tests do you need for a definitive diagnosis in the case of nephrocalcinosis? Serum electrolytes and serum urea, creatinine, urinalysis for calcium, uric acid, oxalate, citrate, uric acid, and phosphate excretion, and determination of tubular phosphate reabsorption [1, 2]. Blood assays for PTH, 25-OH vitamin D, vitamin A (for patients with hypercalciuria), serum B6 levels, thyroid function tests and plasma oxalate (for patients with primary hyperoxaluria), and molecular genetic testing are useful in specific cases [3]. In our patient, urinary oxalate and citrate excretion rates were within normal limits. Molecular cytogenetic analysis and fluorescence in situ hybridization (FISH) revealed deletion in the 7q11.23 region which confirmed the diagnosis of WBS.