Vitamin D Dependent Rickets 2a

**Semantic type:** Disease or Syndrome

**Definition:** Rickets caused by a defect in the VDR gene, encoding the vitamin D receptor. This form of rickets is characterized by hypocalcemia, elevated 1,25-dihydroxyvitamin D (calcitriol) concentrations and may also manifest with alopecia.

**Synonyms:** - Hereditary 1,25 Dihydroxyvitamin D-Resistant Rickets with Abnormal Vitamin D Receptor with Alopecia - VDDR2a - Vitamin D Receptor Deficiency Rickets