Vitamin D-dependent rickets as a possible risk factor for multiple sclerosis.

BACKGROUND

Vitamin D-dependent rickets type I (VDDR I) (OMIM 264700) is a rare hereditary condition caused by a mutation in CYP27B1. Vitamin D is emerging as an important risk factor for susceptibility to multiple sclerosis (MS), but there have been no studies on the possible association between hereditary rickets and this disease.

OBJECTIVE

To investigate the association between VDDR I and MS.

DESIGN

Case studies.

SETTING

Haukeland University Hospital, Bergen, Norway.

PATIENTS: Three patients in 2 families with a co-occurrence of VDDR I and MS.

RESULTS

All 3 patients had VDDR I verified by genetic testing and fulfilled the Poser criteria for MS. Two of the patients have undergone magnetic resonance imaging, which confirmed the diagnosis of long-lasting MS.

CONCLUSIONS

Vitamin D-dependent rickets type I is a very uncommon genetic subtype of rickets. We have identified 3 patients with this disease who later developed MS. We propose that VDDR I and possibly other hereditary rickets mutations that influence vitamin D metabolism could be risk factors for this disease.