Epilepsy and trisomy 19q - different seizure patterns in a brother and a sister

In symptomatic epilepsies due to chromosomal aberrations, epileptogenesis m ay be either the direct consequence of deletion or duplication of a gene ca using seizures or may have a more complex etiology caused by the disturbanc e of the interaction of several genes and environmental factors. We report on a brother and a sister with trisomy 19q13.3 --> qter who present differe nt epileptologic features and discuss epileptogenesis in this syndrome with respect to genes known to be located on the distal part of chromosome 19q. Both patients share mental retardation and several dysmorphic features, Th e boy was hypoxic at birth and showed an extremely delayed psychomotor deve lopment. The girl, however, had no significant neonatal problems, and her p sychomotor development was better. Although the male had an abnormal EEG in childhood, his first partial seizures occurred only as late as at age 31 y ears. He subsequently became seizure-free with carbamazepine (CBZ). In cont rast, the girl already suffered from absence-like seizures during childhood and became seizure-free under ethosuccimide (ESM). A photoparoxysmal respo nse, however. is still visible in her EEG. The difference between the epile ptologic features in these siblings points to epileptogenic mechanisms plac ed far downstream on the way from genotype to phenotype. The photoparoxysma l response-otherwise a facultative finding in genetically determined epilep sies-in the EEG of the sister, however, points to a closer relationship bet ween the duplicated genes and epileptogenesis. The fact that genes encoding potassium channels are located on 19q13.3-q13.4 may also support the latte r assumption. (C) 2001 Elsevier Science B.V. All rights reserved.