Latitude and HLA-DRB1 alleles independently affect the emergence of cerebrospinal fluid IgG abnormality in multiple sclerosis

Background: It is unclear whether the prevalence of oligoclonal IgG bands (OCBs) in multiple sclerosis (MS) is different between northern and southern regions of Asia. Objective: This study aimed to compare the prevalence of OCBs and positive cerebrospinal fluid (CSF) findings between northern and southern regions of Japan and to investigate the association of these CSF findings with HLA-DRB1 alleles. Methods: The study included 180 MS patients from Hokkaido (northern Japan) and 184 patients from Kyushu (southern Japan). The IgG index was defined as increased if it was >0.658. Presence of CSF OCBs and/or increased IgG index was defined as positive CSF findings. Results: Positive CSF findings and OCB positivity were significantly higher in MS patients from Hokkaido than in those from Kyushu ( p < 0.0001 for both). Logistic regression analysis revealed that after adjusting for covariates that can be related to abnormal CSF IgG production, the geographic region (Hokkaido) showed odds ratios (ORs) of 4.08 and 2.57, whereas the HLA-DRB1*04:05 allele showed ORs of 0.36 and 0.30 for positive CSF findings and OCB positivity, respectively. Conclusions: The results indicate that latitude and HLA-DRB1 alleles independently affect the emergence of CSF IgG abnormalities in Japanese patients with MS.