To date only 25 patients with the disorder have been identified. The main clinical features of EPMR are a normal early childhood followed by childhood onset epilepsy and subsequent mental retardation. Epilepsy begins between ages 5 and 10 and is characterized by generalized tonic-clonic seizures, which increase in frequency until the onset of puberty. In addition, a third of all patients suffer complex partial seizures.
All epileptic activity decreases during early adulthood.
Mental retardation begins 2-5 years after the first seizures and continues through adulthood. All the adult patients need help in their daily lives. Of the antiepileptic drugs used, clonazepam has been the most effective. Using the contig to physically map densely spaced microsatellite markers, we have continued to narrow the disease gene region by precisely mapping meiotic breakpoints that refine the locus and by identifying regions homozygous by descent at the disease locus. Two new recombinant breakpoints were identified in unaffected members of the EMPR pedigrees which further narrowed the disease locus region to less than 700 Kb.