16p11.2 Microdeletion/Microduplication Syndrome and Benign Infantile Epilepsy

The 16p11.2 microdeletion/microduplication syndrome is one of the most commonly observed genomic disorders derived from nonallelic homologous recombination surrounded by segmental duplications. Initially, the typical 16p11.2 microdeletions/microduplications were believed to be associated with a 1% prevalence in the autistic spectrum disorder. However, phenotypic heterogeneity and variable penetrance are recognized in autistic spectrum disorder, and there are carriers of 16p11.2 microdeletions/microduplications who showed no definitive phenotypic features. The typical 16p11.2 microdeletions/microduplications are ∼600 kb in size comprising 29 genes, including the proline-rich transmembrane protein 2 ( PRRT2 ) gene. Loss-of-function mutations of PRRT2 cause benign infantile epilepsy and/or paroxysmal kinesigenic dyskinesia. This suggests that haploinsufficiency of PRRT2 due to 16p11.2 microdeletions/microduplications can cause infantile epilepsy and/or paroxysmal kinesigenic dyskinesia. Indeed, some patients who harbor 16p11.2 microdeletions/microduplications are associated with such phenotypic features. Epilepsy in patients with 16p11.2 microdeletions/microduplications is self-limited and easy to manage with antiepileptic drugs. We review the association between benign infantile epilepsy and the 16p11.2 microdeletion/microduplication syndrome, together with the presentation of our own experience.