Endocrine Abstracts

Hereditary vitamin D-resistant rickets (HVDRR) is a rare recessive genetic disorder caused by mutations in the VDR that result in end organ resistance to 1,25-(OH)₂D₃ action. Here, we describe a patient with HVDDR with severe alopecia and rickets. Patient was 3 years old male presenting with gait disorder. He had hypocalcemia (8 mg/dl), secondary hyperparathyroidism (1232 pg/ml), and elevated serum alkaline phosphatase (661 U/l) and 1,25-dihydroxyvitamin D3 (>250 pg/ml). DNA sequence analyses of the vitamin D receptor (VDR) gene of ligand binding domain (LBD) showed that the patient had homozygous mutation for Q152X at exon five. This mutation was a C to T transition resulting in a premature stop at codon 152. Although his parents were non-consanguineous, both of his parents were found to be heterozygous for the mutation. The patient was initially treated with calcitriol (80 ng/kg per day) and high dose oral calcium (150 mg/kg per day) for 1 year. At the end of the first year, intermittent i.v. calcium therapy (5 days/month) was started, because of insufficient clinical and radiological improvement. After 2 years from intermittent i.v. calcium therapy, there was a clear clinical improvement based on clinical and X-ray findings as well as permenant improvement in biochemical findings. However, alopecia in our patient remained unchanged, despite treatment and improvement of rickets. We report the case of HVDRR with a mutation in the LBD and severe alopecia that was successfully treated with intermittent (5 days/month) i.v. calcium treatment.