Aboriginals with multiple sclerosis - HLA types and predominance of neuromyelitis optica

Background: MS is common in people of northern European ethnicity who live in northern geographic areas; however, MS is rarely identified among aborig inal peoples living in the same areas. Objectives: To determine the prevale nce, clinical features, HLA type, and viral infections associated with MS a mong aboriginals in Manitoba, Canada. Methods: A retrospective study was pe rformed in which the clinical features of all aboriginal patients with MS t ogether with HLA type and human herpesvirus-6, HTV-1, human T-cell lymphotr opic virus-1, and endogenous retrovirus associated with MS (MSRV) infection s were analyzed and compared with results from nonaboriginal patients with MS. Results: Seven aboriginals with MS were identified with a period preval ence among aboriginals of 40:100,000. Clinical features included relapsing- remitting (n = 6) or primary progressive (n = 1) phenotypes with aggressive disease courses and frequent involvement of optic nerves and spinal cord ( n = 5) compared with nonaboriginal patients. Autopsy of one patient showed necrosis and eosinophil infiltrates in a cervical spinal cord lesion and a demyelinated optic nerve. Analysis of HLA alleles at the DRB1 and DQB1 loci indicated that the HLA types detected were common in aboriginals, but ther e were no HLA alleles previously associated with the development of MS. Ana lysis of the copy number of MRSV did not show differences among aboriginals and nonaboriginals with or without MS. Conclusions: Aboriginals of Algonki an background are at increased risk for an aggressive type of MS, resemblin g neuromyelitis optica, which is resistant to conventional MS treatments an d occurs independently of HLA alleles previously associated with MS.