Parent-child concordance in multiple sclerosis.

It is now recognized that susceptibility to multiple sclerosis (MS) is determined in part by genetic factors. The gene loci influencing MS susceptibility are largely unidentified. In an attempt to better understand the mode of transmission, parent-child concordance for MS was studied in two large, population-based MS clinic populations. Among 75 parent-child pairs concordant for MS, we found 40 mother-daughter pairs, 13 mother-son pairs, 21 father-daughter pairs, and 1 father-son pair. Controlling for the known female preponderance in MS, the data show a paucity of father-son pairs. These data have implications for understanding the mechanisms of inheritance for MS susceptibility as well as for risk counseling in families of patients.