UNUSUAL EEG PATTERN LINKED TO CHROMOSOME 3P IN A FAMILY WITH IDIOPATHIC GENERALIZED EPILEPSY

Objective: To map the gene causing an unusual EEG pattern of delta bur sts that appears to segregate as an autosomal dominant trait in an Ita lian family. The EEG pattern was observed in four family members affec ted by idiopathic generalized epilepsy (IGE) and in six other clinical ly unaffected members, Methods: All available family members underwent clinical and EEG examination. DNA samples were obtained and used to p erform a whole-genome scan with 270 microsatellite markers. After the first linked marker was identified, 12 additional markers in the same chromosomal region were tested to confirm linkage and define a candida te interval. Results: The gene responsible for the EEG trait was mappe d to an 11-cM interval on the proximal short arm of chromosome 3 (3p14 .2-p12.1). Conclusion: In this family, a characteristic EEG activity i s due to the effect of a single gene on chromosome 3p, A gene encoding a Ca2+ channel subunit maps in the interval and is a potential candid ate for the trait. The clinical expression of epilepsy in four family members may reflect the interaction of additional genes, though enviro nmental or other factors cannot be excluded.