Risk for relatives of patients with multiple sclerosis in central Sardinia, Italy.

Multiple sclerosis (MS) is a chronic, inflammatory, disabling disease of the central nervous system, known for its complex interplay between genetic and environmental factors. We used life table techniques to calculate age-adjusted recurrence risks for different categories of relatives of MS patients from Central Sardinia (Italy), a genetically homogeneous, stable population with a high degree of consanguinity. We included 313 probands and a total of 12,717 relatives in the analysis. The overall age-adjusted recurrence risk for relatives of MS probands is 1.90% [95% confidence interval (CI): 1.57-2.30]. The age-adjusted recurrence risk in parents was 1.26% (95% CI 0.60-2.63), in children 2.33% (95% CI 0.09-5.56), in sibs 4.76% (95% CI 3.57-6.32), in second-degree relatives 0.72% (95% CI 0.42-1.22), and in third-degree relatives 1.79% (95% CI 1.27-2.51). The sex of the probands (male) and of the relatives (female), and the number of affected relatives in the family significantly increase the risk of MS in relatives. Copyright 2003 S. Karger AG, Basel