Increased prevalence of unprovoked seizures in patients with a 22q11.2 deletion

Many neurologic abnormalities have been identified in patients with a deletion of chromosome region 22q11.2, including recurrent, apparently unprovoked seizures. We reviewed the database of patients with a 22q11.2 deletion at the Children's Hospital of Philadelphia to assess the prevalence of idiopathic epilepsy in this population. The records of 383 patients with a confirmed 22q11.2 deletion were reviewed for documentation of seizures; precipitating events such as hypocalcemia, fever, and recent surgery; MRI and EEG findings (to aid in seizure classification); and potential risk factors for epilepsy. Of 348 patients with adequately detailed histories, 27 patients had apparently unprovoked seizures (7% of the total population). A disproportionate number of these patients met criteria for generalized epilepsy. Cardiac disease and prematurity were not risk factors for the development of unprovoked seizures in this population. The prevalence of unprovoked seizures in individuals meeting criteria for epilepsy in patients with a 22q11.2 deletion evaluated at our institution is much greater than in the general population. The association with generalized epilepsy suggests that this increased risk is a primary manifestation of the genetic syndrome, not a secondary result of the other manifestations of 22q11.2 deletions. These results suggest that diagnostic screening for the 22q11.2 deletion syndrome should be considered in patients with epilepsy and other signs suggestive of this interstitial deletion syndrome, and have implications for the identification of potential genetic loci for idiopathic epilepsy.