The deletion contains four genes: non-imprinted in Prader-Willi/Angelman syndrome 1 gene (NIPA1), non-imprinted in Prader-Willi/Angelman syndrome 2 gene (NIPA2), CYFIP1 and tubulin gamma complex associated protein 5 gene (TUBGCP5)3. Here, TUBGCP5 is linked to Down syndrome.