EVIDENCE FOR NORMAL VITAMIN-D-RECEPTOR MESSENGER-RIBONUCLEIC-ACID ANDGENOTYPE IN ABSORPTIVE HYPERCALCIURIA

Absorptive hypercalciuria (a stone-forming condition) is characterized by gut hyperabsorption of calcium, hypercalciuria, and reduced bone d ensity. Inasmuch as these features implicate enhanced calcitriol actio n in gut and bone, we analyzed the vitamin D receptor (VDR) gene to as certain whether an abnormality of this gene marks patients with intest inal hyperabsorption of calcium. We have compared the frequency of a r estriction fragment length polymorphism (Bsm I) associated with differ ent alleles of the VDR gene in a group of 33 well characterized absorp tive hypercalciuric patients and a group of 36 normal race- and age-ma tched control subjects. There was difference between the distribution of the VDR alleles in the patient population when compared with the no rmal population The coding region of VDR messenger RNA was also normal , as determined by both DNA sequence analysis and chemical mismatch cl eavage analysis of copy DNA from II index absorptive hypercalciuric pa tients. On the basis of these results, we propose that the enhanced in testinal calcium absorption invariably seen in absorptive hypercalciur ia and attendant symptoms of this disorder are not attributable to mut ations of the VDR and are not Linked to a common VDR genotype.