Abstracts

Rationale: We aimed to identify the prevalence and distribution of periventricular nodular heterotopia (PNH) in patients with 22q11.2 microdeletion syndrome (22q11.2DS). Methods: We retrospectively analyzed the data of 35 adult patients with 22q11.2DS. Patients without brain MRI or with poor quality images were excluded from the study. We also included 2 other patients with PNH identified through postmortem study, previously reported by our group. 22q11.2 microdeletion was confirmed by FISH analysis other pathologic genetic findings were ruled out through genome-wide microarray or whole genome sequencing. Results: Out of 30 patients who met study entry criteria, 7 had PNH. Out of these 7 patients, two patients did not have seizures. In the remainder, the mean age of seizure onset was 14.4 (2-42) years. The nodules were located over the frontal horn of lateral ventricles, in all 7 patients. The nodules were small, non-contiguous, varying in number from 1 to10. They were unilateral in 5/7 patients. Conclusions: Our study demonstrates that PNH in patients with 22q11.2DS have a characteristic pattern: small number, small size, non-contiguous, and located over the frontal horn of the lateral ventricles. This finding may help diagnosis in patients who do not have genetic testing. Furthermore, the description of these 7 patients, make 22q11.2 microdeletion the 3rd most common CNV reported to date in association with PNH  (after 6q terminal deletion and 17q21.3 deletion). Funding: Brain and behaviour foundation (DMA)