What extra dose of the affected genes does a trisomic individual carry?

1. A euploid individual carries two copies of each autosomal gene, which is the normal dose. 2. A trisomic individual carries three copies of the genes on the affected chromosome. 3. Three copies compared with two is an extra dose of 150 percent. 4. That excess can lead to a number of functional challenges and often precludes development. 5. A figure of 200 percent would mean four copies, which trisomy does not produce. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 13 "Modern Understandings of Inheritance", section 13.2 Chromosomal Basis of Inherited Disorders_