ESPE Abstracts

Background: Vitamin D dependent rickets type II (VDDR II) is a rare autosomal recessive disorder, inherited due to mutation on vitamin D receptor (VDR) leading to end organ unresponsiveness to vitamin D. It is characterized by an early onset refractory rickets, hypocalcaemia, hypophosphatemia, growth retardation, hyperparathyroidism and elevated circulating levels of 1,25-dihydroxyvitamin D3 which is the hallmark of the disease.

Objective and hypotheses: The aim of study is to describe clinical, genetic, biochemical and long term management of eight Saudi children diagnosed with VDDR II.

Method: All patients underwent complete clinical evaluation including: age at diagnosis, initial rickets symptoms and signs, family history of VDDR II, presence or absence of alopecia and their growth parameters, biochemical workup including: serum calcium, phosphate, alkaline phosphatase (ALP) and parathyroid hormone (PTH) levels and genetic study of VDR mutation; done by Paediatric Endocrinologists in King Faisal Specialist Hospital and Research Centre in Riyadh/Saudi Arabia. We presented patients data at baseline, first, second, fifth and tenth year interval post calcium infusion treatment (management protocol will be attached).

Results: All patients had full clinical and biochemical features of rickets including alopecia. The mean age of diagnosis was 3.6 year. Most of the patients had growth retardation at diagnosis (height below −2 S.D. below mean). Clinical and biochemical parameters were improved in all cases (detailed data will be attached). The mutation in VDR (Y295X Homozygous) was positive in all patients.

Conclusion: Early diagnosis of VDDR II with early treatment of IV calcium infusion will improve growth velocity; decrease rachitic manifestation and normalized calcium, phosphate, PTH and ALP levels (but not alopecia). More studies require to see the effect of early vs. late treatment on bone density.