We aimed to characterize the clinical profile and human leukocyte antigen (HLA)-DRB1 genotype of patients with late onset multiple sclerosis (LOMS) in Western Australia. The clinical features, laboratory studies and HLA-DRB1 alleles were analysed in patients with multiple sclerosis (MS) with onset over 50years of age and compared with 100 patients with early onset MS (EOMS). Of a cohort of 829 patients with MS, 73 (8.8%) presented at over 50years of age, including 14 (1.7%) over 60years. Patients with LOMS had a lower female to male ratio, more frequent initial motor dysfunction, less frequent sensory symptoms and optic neuritis, a more frequent primary-progressive course and shorter time to reach Extended Disability Status Scale (EDSS) scores of 3.0 and 6.0. More LOMS patients were initially misdiagnosed compared to patients with EOMS. HLA-DRB1 *1501 was strongly associated with both LOMS and EOMS compared to the Control subjects, while HLA-DRB1 *0801 was over-represented in patients with LOMS. We concluded that patients with LOMS have a different clinical profile when compared to those with EOMS. Carriers of HLA-DRB1 *0801 may be more prone to develop MS at a later age.
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