Myotonic dystrophy: opportunities for prenatal prediction.

Prenatal prediction of the inheritance of myotonic dystrophy in a family with affected individuals feasible in special cases when analysis of linkage to the secretor gene (determing ABH substances) can be carried out. We report a large kindred having multiple members affected with variable degrees of severity of myotonic dystrophy and having several matings for which linkage analysis is feasible. Even though this approach is not applicable for most families and although the process of genetic recombination complicates the analysis, in individual cases the use of linkage in prenatal or postnatal prediction of myotonic dystrophy may be very helpful for early diagnosis, more precise genetic counseling, and family planning.