Hypercalciuria and kidney calcifications in terminal 4q deletion syndrome: further evidence for a putative gene on 4q.

We report a newborn girl with a de novo terminal 4q deletion (q31.3 --> qter) and a characteristic phenotype of minor facial anomalies, cleft palate, congenital heart defect, abnormalities of hands and feet, and postnatal onset of growth deficiency. Laboratory studies showed excessive urinary calcium excretion on standard milk formula and on oral calcium load. Blood measurements of parathyroid hormone, calcitonin, bicarbonate, calcium, phosphorus, magnesium, sodium, chlorine, potassium, and urinary measurements of phosphorus, magnesium, sodium, chlorine, potassium were normal for age. At 2 months of life, ultrasonography showed kidney calcifications. Clinical and laboratory data support the diagnosis of absorptive hypercalciuria or abnormal regulation of calcium-sensing receptors in the renal tubules. The evidence of hypercalciuria and kidney calcifications associated with 4q terminal deletion strengthens the hypothesis that a putative gene for hypercalciuria is located on the terminal segment of chromosome 4q.