ESPE Abstracts

Vitamin D dependent rickets type 1A (VDDR-1A) is a very rare autosomal recessive disorder caused by mutations in the CYP27B1, which encodes vitamin D 1α-hydroxylase. A study was conducted to understand the clinical and genetic profile of patients with 1 alpha hydroxylase deficiency.

Method: A retrospective evaluation of the clinical presentation, treatment and genetic profile of patients diagnosed with 1 alpha hydroxylase deficiency (VDDR 1A) under follow-up with the the Paediatric Endocrinology team

Result: We report 7 cases of 1 alpha hydroxylase deficiency. Four of whom presented with rickets. one presented with difficult to treat hypocalcaemia seizures, one presented with hypocalcaemia of infancy and one presented with delayed walking. Hypophosphatemia rickets was considered a possibility in 2 of the patients initially. CYP27B1 gene mutation was detected in 6 of the patients. One of the patient had a symptomatic cousin who was found to have a CYP27B1mutation and hence assumed to be carrying the same gene. All of them were treated with Alfacalcidol and calcium which was titrated based on their response. All the 7 patients responded well to it.

Conclusion: VDDR1-A although rare must be considered as a possibility especially when, patients present with difficult to treat hypocalcaemia with a normal or high 25 hydroxyD3 levels. Genetic analysis must be considered for a definitive diagnosis especially in difficult cases.