This document discusses aneuploidy, which is an abnormal number of chromosomes. It defines aneuploidy and provides examples of monosomy and trisomy. Monosomy is having one fewer chromosome, like Turner Syndrome which is missing an X chromosome. Trisomy is having one extra chromosome, the most common being Down Syndrome which is trisomy 21. The document outlines objectives and provides details about different types of aneuploidy conditions.