Maternal UBE3A deficiency can result from deletions in the chromosomal region 15q11–q13 containing UBE3A, which account for about 70% of Angelman syndrome patients, mutations in UBE3A gene, paternal uniparental disomy of chromosome 15, or an imprinting defect (Williams et al., 2006; Bird, 2014; Buiting et al., 2016). This evidence concerns the gene UBE3A and Angelman syndrome.