Epidemiology of multiple sclerosis in Arabs in Jordan: a comparative study between Jordanians and Palestinians.

In a 2-year hospital-based study in Jordan 131 Arab multiple sclerosis patients were identified including 84 Palestinians and 36 Jordanians. Based on MS/ALS case ratio, multiple sclerosis was found to be twice as common among Palestinians than Jordanians. Other than the less marked female preponderance among Jordanian patients, the disease had the same clinical and paraclinical characteristics in both groups. It was more likely for Palestinian and Jordanian patients to originate from the northern parts of their countries, to be Rh negative and to be HLA-DR2 positive than their controls. Palestinians (patients and controls) did not show significant differences from Jordanians (patients and controls) in relation to their eye color, ABO and Rh blood groups distribution nor the HLA-DR or HLA-DQ (apart from HLA-DQ3) epitopes frequency, thus not offering any significant difference in the genetic-racial markers studies to explain the difference in the observed disease susceptibility. Previous studies demonstrated that 2 racially different populations sharing the same environment can have different risk of developing multiple sclerosis, but this study has shown that this can also be true for 2 racially similar populations sharing the same environment.