Vitamin D dependent rickets type II and normal vitamin D receptor cDNA sequence. A cluster in a rural area of Cauca, Colombia, with more than 200 affected children.

Vitamin D dependent rickets type II is an autosomal recessive disease caused by the vitamin D defective receptor. More than 200 patients with different types of lower limb deformities were detected in a rural area of the Cauca department in the southwest part of Colombia. Patients were well nourished and in good physical condition in spite of their deformities. None of them presented alopecia, myopathy, seizures or aminoaciduria. Serum analysis showed significantly lower serum calcium as compared to normal relatives, though in the normal low range, normal phosphorus, high alkaline phosphatase, normal 25-hydroxyvitamin D3 and high 1,25-dihydroxyvitamin D3, indicating target organ resistance. The cDNA analysis showed normal nucleotide sequence. We suggest that our patients represent a distinct form of receptor-positive resistance to vitamin D. This report is the first extensive study on this class of patients.