Avian Erythroblastosis Virus E26 Oncogene Homolog 2. Researchers have "demonstrated that overexpression of ETS2 results in apoptosis. Transgenic mice overexpressing ETS2 developed a smaller thymus and lymphocyte abnormalities, similar to features observed in Down syndrome."[8] ETS2-Transgenic mice were also shown to "develop neurocranial, viscerocranial and cervical skeletal abnormalities", similar skeletal abnormalities to those seen in Down's Syndrome