Progressive myoclonus epilepsy of Unverricht-Lundborg type: a clinical and molecular genetic study of a family from the United States with four affected sibs.

We describe clinical and molecular genetic data on a family from the United States in which four of five sibs are affected with progressive myoclonus epilepsy of Unverricht-Lundborg type. The gene for this disorder (EPM1) has previously been mapped to the distal region of chromosome 21. Molecular genetic results suggest that the disease gene in this family is linked to the same region of chromosome 21. Crossover events in the family help refine the gene localization by placing EPM1 between loci CBS and D21S112.