What is considered the outcome of trisomy 21?

Trisomy 21, commonly known as Down syndrome, is characterized by the presence of an extra copy of chromosome 21 in a person's cells. This genetic condition results from nondisjunction during cell division, where chromosomes fail to separate properly, leading to a gamete with an extra chromosome. When this gamete unites with a normal gamete during fertilization, the resulting zygote has three copies of chromosome 21, hence the term "trisomy 21."

Individuals with Down syndrome often exhibit a distinct set of physical characteristics, developmental delays, and may have associated health issues. Recognizing Down syndrome as a genetic disorder helps in understanding its implications, the potential for supportive therapies, and the importance of genetic counseling for affected individuals and their families.

The other options represent different biological concepts that do not pertain specifically to trisomy 21 and do not encompass the unique features and implications associated with this genetic disorder.