A novel 800 kb microduplication of chromosome 16q22.1 resulting in learning disability and epilepsy may explain phenotypic variability in a family with 15q13 microdeletion.

The phenotype of 15q13.3 microdeletion is variable and can be non-penetrant. Recently, "second-hit hypothesis" has been proposed as a possible explanation for some variability in recurrent microdeletion syndromes.