4p(-) syndrome: a chromosomal disorder associated with a particular EEG pattern.

We report an electroclinical and cytogenetic study of 4 patients with Wolf-Hirschhorn syndrome (WHS). In all cases, we observed a stereotyped EEG and clinical picture characterized by generalized or unilateral myoclonic seizures followed later by brief atypical absences. Electrographically, these were accompanied by a sequence of centroparietal or parietotemporal sharp waves; high-voltage wave with a superimposed spike becoming unusual spike-wave complexes, often elicited by eye closure; burst of diffuse spikes and waves; and frequent jerks. This electroclinical pattern is very similar to the one described in Angelman syndrome (AS) in which a defect in GABAA receptor function has been suggested. Moreover, the genes encoding the GABAA receptor subunit have been mapped to the p12-p13 bands of chromosome 4. Even though the deletion in these cases does not encompass the 4p12-p13 region, we suggest that the electroclinical picture common to WHS and AS might represent a characteristic type of epilepsy linked to a common genetic abnormality.