The development process of TAM in ML-DS patients is as follows: first, the normal embryo obtains extra chromosome 21; second, the fetus with trisomy 21 develops mutations in the GATA1 gene; and finally, the child with trisomy 21 and the GATA1 mutation develop ML-DS[8–11] when they have mutations in other related genes, such as RAD21, EZH2, KRAS, and CTCF. The gene discussed is RAD21; the disease is Dravet syndrome.