Investigation of the 15q13.3 CNV as a genetic modifier for familial epilepsies with variable phenotypes

Incomplete penetrance and variable phenotypic expression are characteristic of a number of syndromes of familial epilepsy. The purpose of the present investigation is to determine if the 15q13.3 copy number deletion functions as a locus modifying the epilepsy phenotype caused by other known or presumed pathogenic mutations segregating in families with epilepsies. No 15q13.3 microdeletions were detected in 756 affected or definite obligate carrier individuals across 151 families selected on the basis of having multiple members affected with epilepsy and showing a range of seizure types. Therefore, the 15q13.3 microdeletion does not act as a genetic modifier in this cohort of families and is not responsible for any of the genetic heterogeneity hypothesized to account for failure to detect linkage in previous genome‐wide scans in five of the larger families included in this study.