Chromosome
This syndrome is caused when there is a deletion in chromosome #15. There is a deletion of the gene UBE3A. You usually get a gene called UBE3A from each parent, but in certain areas of the brain only the copy inherited from the mother is active (maternal). If the UBE3A is lost from the mother then this enzyme involved in targeting proteins for degradation (break down) within the cell will not work. There are also cases where both the mother and the father give the child paternal UBE3A, which does not become active at all.