Trisomie 21, also known as Down syndrome, is a genetic condition caused by the presence of an extra copy of chromosome 21. This additional genetic material affects physical and cognitive development, leading to characteristic features such as a flat facial profile, slanted eyes, and a shorter stature. Individuals with Trisomie 21 may also experience varying degrees of intellectual disability. People with Trisomie 21 often benefit from early intervention programs, which can help improve their skills and independence. With appropriate support, many individuals lead fulfilling lives, participate in education, and engage in their communities. Awareness and understanding of Trisomie 21 have increased, promoting inclusion and acceptance.