Abstracts

RATIONALE: Clinical findings in patients with a deletion of chromosome 22q11.2 (Digeorge syndrome, velocardiofacial syndrome) have been well-described, including cardiac anomalies, palatal abnormalities, immune deficiencies, and characteristic facial features. However, beyond descriptions of a wide range of non-specific structural brain abnormalities, typical neurologic features have not been well-established. Recently, there have been several reports of recurrent, unprovoked seizures, characterized as idiopathic partial and atypical absence epilepsy, in patients with this deletion. The large database of patients with chromosome 22q11.2 deletion syndrome evaluated at the Children[ssquote]s Hospital of Philadelphia provided the opportunity to assess the prevalence of idiopathic epilepsy in a population of almost 400 patients with the deletion. We hypothesized that the prevalence would be increased compared to that of the general population. Participants should be able to discuss the relationship of chromosome 22q11.2 deletions and idiopathic epilepsies, and its potential influence on their clinical practice or genetic research.
METHODS: The clinical records of 376 patients were reviewed for documentation of seizure activity; potential triggers such as hypocalcemia, fever, and recent surgery; as well as MRI and EEG findings to aid in seizure classification. Head circumference, neuropsychological test results, family history, and cardiac and palatal abnormalities were also noted. Phone follow-up was performed to clarify details.
RESULTS: Of 344 patients whose histories were adequately detailed, 83 (24%) had seizures. 24 (29%) of those patients with seizures had associated hypocalcemia. 19 (23%) patients[ssquote] seizures occurred in the post-operative period and 15 (18%) occurred with fever. 25 (30%) patients had unprovoked seizures, comprising 7% of the total population analyzed.
CONCLUSIONS: The lifetime prevalence of unprovoked seizures in the general population has been estimated to be 0.84% to 1.5%. The prevalence of unprovoked seizures in patients with 22q11.2 deletion evaluated at our institution is much greater. Further definition of seizure phenotypes will determine whether this increased risk represents a secondary manifestation of features of chromosome 22q11.2 deletions or a primary process. These results have implications for consideration of a chromosome 22q11.2 deletion syndrome in patients seen primarily for epilepsy, and for the identification of potential genetic loci responsible for idiopathic epilepsy.
[Supported by: Grant number: DC02027]; (Disclosure: Grant - Grant number: DC02027)