RICKETS WITH LOW 25 VITAMIN D, IS NOT ALWAYS A DEFICIENCY, IT COULD BE INHERITED RICKETS DISORDERS

Amal Daghriri, Fadhel Hazazi, Zainanb Saaed, Badi Alenazi, Nasir AM. Aljurayyan and Amer O. AL Ali*

ABSTRACT

Rickets is a common disorder of bone mineralization, mostly caused by Vitamin D deficiency, but not uncommon could also result from the other genetically inherited disorder disorder of vitamin D activation, action. One of this disorder is Vitamin D dependent rickets type IB (VDDR-1B). It is a very rare condition that has only been reported to affect around 6 families to date. It is an autosomal recessive disorder caused Mutations of CYP2R1 leading to subnormal level and function of 25 hydroxylase enzyme. like other causes of Rickets patients would present clinically with hypotonia, muscle weakness, growth failure, hypocalcemia seizures in early infancy, and radiographic findings of rickets. Here we report a 2 year old Saudi female who present with valgus deformity of the feet and delayed motor development with biochemical, radiological evidence of vitamin D disorder. Since vitamin D level was low she was assumed and treated as being due to deficiency with cholecalciferol plus one alpha for 1 year, but there was no improvement. Then diagnosis was changed to Vitamin D dependent Rickets 1B, and treatment with Calcitriol show great improvement within 3 weeks, Alkaline phosphatase and PTH both drop to normal levels. 3 months after Calcitriol treatment, radiological evidence of the resolution was clear and the patient start to move by then. In this paper, we raise the awareness that Rickets with low vitamin D25 level not always mean deficiency, especially if patient fail to improve with cholecalciferol, and in such case, a rare inherited disorder of Vitamin D activation and action should be looked for.

Keywords: Rickets, CYP2R1, VDDR1B, 25-hydroxylase enzyme.