What condition is characterized by the presence of an extra 21st chromosome?

The condition characterized by the presence of an extra 21st chromosome is Down Syndrome. This genetic anomaly, known as trisomy 21, results in three copies of chromosome 21 instead of the typical two. Down Syndrome is associated with distinct physical characteristics, developmental delays, and a higher likelihood of certain medical conditions.

Understanding how Down Syndrome arises from the genetic level is essential for recognizing its implications in educational and psychological assessments, as well as providing appropriate support and interventions. In educational settings, awareness of Down Syndrome allows educators to tailor their approaches to accommodate the unique learning needs and strengths of students with this condition, promoting inclusive practices and fostering an environment conducive to their growth.