User:Mary.duffy726/sandbox

Introduction
A mouse model has frequently been used to study Down syndrome due to the close similarity in genomes of mice and humans and prevalence of mice usage in laboratory research. Trisomy of human chromosome 21 is responsible for causing Down syndrome, and mouse chromosome 16 closely resembles this chromosome. In 1979, trisomy of the mouse chromosome 16 (Ts16) initially showed potential to be a model organism for human Down syndrome. However, Ts16 embryos rarely survive until birth, making them unable to serve as a model for behavior and development. This dissimilarity in survival between species arises from the presence of genes on mouse chromosome 16 not present on human chromosome 21, introducing additional gene dosage imbalance. Because of this disadvantage, more specific mouse models have been utilized recently.