The less frequent microdeletion 15q11.2, containing four protein-coding genes (NIPA1, NIPA2, CYFIP1, and TUBGCP5), is associated with Burnside–Butler syndrome (BBS), which partially overlaps with certain neurodevelopmental disorders, including Prader-Willi and Angelman syndrome [40]. Here, NIPA1 is linked to neurodevelopmental disorder.