Age-adjusted familial rates for MS were determined in children and siblings of patients studied at the MS Clinic and Dept of Genetics, Health Sciences Centre Hospital, Univ British Columbia, Vancouver BC, Canada. The risk for these relatives to develop MS was 3 to 5%, which was 30-35 times the 0.1% rate for the general population in this relatively “high-risk“ area. For female index patients with MS, the proportion of children affected was 5/797 or 0.6% (all girls) but the age-adjusted risk was 2.6%, four times the crude rate. The proportion of daughters affected was 5/386 (1.3%) with an age-adjusted risk of 5%. 
COMMENT. The onset of MS in childhood is unusual, but the 50-fold increase in risk for daughters of female patients with MS should alert neurologists to this diagnosis in young children with suggestive symptoms. The concordance rate for MS among monozygotic twins is 26% compared to 2% for dizygotic twins.