The Lafora disease is an uncommon genetic condition. Four cases (two families) were detected in Zarcero, a small town in Costa Rica (population under 2000). They belonged 10 two separate consanguineous marriages but both families had common ancestors. The. diagnosis ·of Lafora disease was confrrmed by liver. biopsy' in one of the patients. The ages of onset .were 13, 14, 16 and 17 years. Patients died after four, nine, six and fi ve years of severe progressive physical and mental deterioration, respectively. The gene for Lafora disease arrive to Zarcero from one of its founders. There are no other cases reported from Co.sta Rica: this is an exampie of genetic drift, or more specifically; founder effect.
Keywords: lafora disease, myoclonic epilepsy, founder effect