The presence of an extra copy of chromosome 21 is most often associated with what characteristic?

• A. Cognitive impairment and distinct facial characteristics
• B. Athletic ability
• C. Enhanced memory
• D. Autoimmune disorders

Answer: (C)

Having an extra copy of chromosome 21 results in Down syndrome, a condition most consistently linked to intellectual disability and distinctive facial features. The extra genetic material affects development, leading to reduced cognitive functioning on average and physical traits such as a flat facial profile and upslanting eyes. While individuals may have a range of other health issues and strengths, enhanced memory or athletic superiority are not typical characteristics. Autoimmune disorders can occur more often than in the general population, but the defining association described here is cognitive impairment with distinctive facial features.