Vitamin D-dependent rickets type II (VDDR II) is an autosomal recessive disorder resulting from the defective response of vitamin D receptors (VDR) in the target tissues to the active hormonal form of vitamin D. Vitamin D is important for enhancing the absorption of calcium from the small intestine and for normal bone development. VDDR II is characterized by the early onset of rickets, alopecia, hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated 1,25-(OH)2D3 levels.
Khan et al, 1996 were the first to report vitamin D-dependent rickets type II (VDDR II) in a consanguineous Bahraini family.
[Khan IM, Al-Hermi B, Al-Abbasi AJ, Al-Rufai M, Al-Arrayed S. Hereditary 1,25-dihydroxyvitamin D-resistant rickets: a report of several cases in a kindred. Bahrain Med Bull. 1996; 18(1):28-30.]
Al Anzy et al, 1998 described the clinical features of three siblings with clinically different severity of vitamin D dependent rikets type II with alopecia.
[Al-Anzy HM, Alsaleh QA, Salem MT, Nadi H, Sameer E. A new variant of 1,25-dihydroxyvitamin D-receptor-defect rickets and alopecia associated with mental retardation and hearing loss. Gulf J Dermatol. 1998; 5(1):30-1.]
Paul and Al-Khusaiby, 1987 reported vitamin D dependent rickets with alopecia in an 18-month-old Omani male born to non-consanguineous parents.
[Paul G, Al-Khusaiby SBM. Vitamin D dependent rickets type II with alopecia. Medical Newsletter. 1987; 3(3):2-6.]
Al-Khenaizan and Vitale, 2003 report two Saudi brothers with vitamin D-dependent rickets type II disease associated with alopecia of the scalp or the body.
Jabur, 2009 described the clinical features of two sisters with osteomalacia.
Aljubeh et al. (2011) reported two unrelated patients with Familial Vitamin D Resistant Rickets. Both patients showed severe growth and motor retardation, rickets with chest deformities, pulmonary abnormalities, with hypocalcemia, secondary hyperparathyroidism, and susceptibility to pulmonary infections. Vigorous treatment with IV calcium led to dramatic improvements in both cases, with normalization of abnormal biochemistries and healing of rickets. Both patients were found to carry the same novel missense p.R274H mutation in the VDR gene.