Familial Vitamin D-dependent rickets Type 2A: A report of two cases with alopecia and oral manifestations

Rickets is a metabolic bone disease that develops as a result of inadequate mineralization of growing bone due to disruption of calcium, phosphorus and/or Vitamin D metabolism. In addition, several rare genetic causes of rickets have also been described, which can be divided into two groups. The first group consists of genetic disorders of Vitamin D biosynthesis and action, such as Vitamin D-dependent rickets Type 1A, Type 1B, Type 2A (VDDR2A) and Type 2B. The second group involves genetic disorders of excessive renal phosphate loss (hereditary hypophosphatemic rickets). VDDR2A is a rare autosomal recessive disorder caused by mutation in the Vitamin D receptor gene, leading to end-organ resistance to 1,25(OH)2Vitamin D3. It clinically represents growth retardation presenting in the 1st year of life and frequently associated with alopecia totalis, which differentiates it from VDDR Type 1. Due to target organ resistance, its response to Vitamin D is poor. We report two cases of familial VDDR2A, with alopecia and oral manifestations.