Similar familial risk in multiple sclerosis subgroups.

BACKGROUND: A subgroup of patients diagnosed with multiple sclerosis (MS) present with no oligoclonal bands (OCB) in the cerebrospinal fluid (CSF). Several studies report different clinical characteristics and genetic associations between the two groups. OBJECTIVE: To investigate whether the OCB negative subgroup has a distinct etiology from band positive MS. METHODS: Using nationwide registers to estimate familial risks, which reflect the genetic contribution of a disease. RESULTS: Odds ratios of MS were similar for relatives to band positive and negative patients. CONCLUSION: From the perspective of familial liability, MS without OCB is etiologically closely related to the dominant subgroup of OCB positive MS.