NDN and Prader-Willi syndrome: The deletion detected at 15q11.1-q11.2 with the aCGH showed that 106 genes are contained in this deletion including several OMIM genes, as well as NBEAP1, responsible for B cell leukemia in translocation events (6, 10), and NDN, belonging to the contiguous genes responsible for the Prader Willi syndrome.