Objective: Multiple sclerosis (MS) is a common disease of the central nervous system.
This disease may be initiated by either vitamin deficiency or triggered by abnormality in
CYP24A1 and vitamin D receptor.
Materials and Methods: In this case-control study, the expression of genes encoding
vitamin D receptor (VDR) and CYP24A1 in relapsing-remitting MS (RR-MS) patients
was compared with normal individuals in the Iranian population. RNA from whole
blood of 50 RR-MS patients (HLA-DRB1*15-negative and responders to interferonbeta
with a normal vitamin D level) and 50 normal controls was extracted. The levels
of CYP24A1 and VDR expression were measured using real-time quantitative polymerase
chain reaction.
Results: The RR-MS group had a significantly more than 2 times higher expression level
of VDR than the normal group (P=0.04). On the other hand, there was a 0.89 times decrease
in the expression level of CYP24A1 in RR-MS patients which was not statistically
significant. There was no linear correlation between the risk of expanded disability status
scale of Kurtzke (EDSS) and the expression level of either CYP24A1 or VDR. In addition,
the expression level of CYP24A1 or VDR was not correlated with the duration of the
disease.
Conclusion: Up-regulation of VDR is likely to happen in RR-MS patients in the Iranian
population. We did not observe a gene expression-phenotype correlation for CYP24A1
which may be due to limited statistical power as a result of the small sample size. Although
the individuals taking part in this study had normal levels of vitamin D, the increase in
VDR expression levels may perhaps be a response to a defect in vitamin D processing.
Another possibility is that despite an increase in VDR expression level, factors such as
micro-RNAs may result in their deactivation while an increase in VDR expression level can
be seen as a compensatory response. Of course, further studies are required to identify
the mechanism of action of vitamin D by analyzing genes involved in its signaling pathway,
particularly VDR and CYP24A1
