Vitamin D dependent rickets type 2A: a case series of two siblings with novel mutation in vitamin D receptor gene responded to high dose oral calcium and calcitriol.

OBJECTIVES: Vitamin D dependent rickets type 2A (VDD2A) is a rare autosomal recessive disorder due to mutation in vitamin D receptor (VDR) gene leading to hypocalcemia, secondary hyperparathyroidism and signs of rickets. We are reporting case series of two siblings with VDDR2A who were managed in a non-conventional manner (oral calcium and oral vitamin D) in a tertiary care hospital of resource limited country.

CASE PRESENTATION: Two male siblings presented at the age of 10 years (case 1) and 11.5 years (case 2) with the complaints of short stature and walking difficulty since 4 and 1.5 year of age respectively. They were born to consanguineous parents with a history of two maternal cousins having the same complaints. The investigations showed frank rickets findings on imaging with biochemical evidence of hypocalcemia, hypophosphatemia, raised levels of alkaline phosphatase and raised parathyroid hormone with normal 25-OH vitamin D levels and raised 1,25(OH)2D3 levels confirming the diagnosis of calcipenic rickets. The whole exome sequencing (WES) of case 1 (younger sibling) showed that he was carrying a novel homozygous variant in VDR gene c.1354C>T, p(Arg452Cys). They both are being managed on high doses of oral calcium supplements and activated form of vitamin D.

CONCLUSIONS: VDDR2A can present with or without alopecia.It can be managed with high doses of oral calcium and vitamin D supplements in resource limited areas.