Neuromyelitis optica spectrum disorders and the HLA system

Neuromyelitis optica spectrum disorders (NMOSD) are a rare group of inflammatory demyelinating diseases of the central nervous system whose etiopathogenesis involves genetic factors. The association between HLA and NMOSD has been studied in various populations. However no association study has been conducted in Tunisia.We therefore conducted a case-control study including 12 NMOSD patients (recruited over a period of 11 years) and 123 unrelated healthy subjects from the South Tunisian population. HLA class I typing was performed using the complement-dependent lymphocytotoxicity technique. HLA class II typing was performed by PCR-SSP. HLA marker polymorphism in our patients was statistically compared with the control group. For the HLA class I region our work suggests the previously undescribed association of two markers with NMOSD: HLA-A23 and HLA-B7. For the HLA class II region no association was found contrary to studies carried out in other populations.Our results call for multicenter collaboration to expand our sample size and validate the HLA associations observed.