title: A familial syndrome of decrease in sensitivity to 1,25-dihydroxyvitamin D.
abstract: Typical features of hereditary vitamin D-dependent (pseudovitamin D-deficient) rickets were observed beginning at ages 20 and 5 months in a brother and sister. Both had calcium malabsorption correctable with high doses of 25-hydroxyvitamin D. During periods of hypocalcemia they both manifested secondary hyperparathyroidism with hypophosphatemia and high serum concentrations of endogenously produced 1,25-dihydroxyvitamin D. In each, normalization of serum calcium concentration and resolution of osteomalacia were obtained with continuous administration of high doses of ergocalciferol or high doses of 1,25-dihydroxycholecalciferol. Chemical features of vitamin D deficiency were corrected in the presence of high circulating concentrations of 1,25-dihydroxyvitamin D2, produced endogenously, or of 1,25-dihydroxyvitamin D3, administered by mouth. Serum concentrations of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D were normal in five first degree relatives. We conclude that in these five first degree relatives. We conclude that in these siblings, rickets and osteomalacia resulted from a hereditary decreased sensitivity to 1,25-dihydroxyvitamin D at the intestine and perhaps other vitamin D target tissues.
mesh_terms: D000042:Absorption; D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D001842:Bone and Bones / Q000000981:diagnostic imaging; D002112:Calcifediol / Q000627:therapeutic use; D002117:Calcitriol / Q000494:pharmacology* / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000652:urine; D004872:Ergocalciferols / Q000097:blood; D005260:Female; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D008297:Male; D010758:Phosphorus / Q000097:blood; D011859:Radiography; D013577:Syndrome
chemical_list: D004872:Ergocalciferols; D010758:Phosphorus; D000242:Cyclic AMP; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium