Which of the following is a genetic condition commonly associated with intellectual disability?

• A. Fetal alcohol spectrum disorders
• B. Down syndrome
• C. Meningitis
• D. Lead poisoning

Answer: (B)

Intellectual disability can arise from genetic differences, and the most common genetic condition linked to it is Down syndrome, which occurs when there is an extra copy of chromosome 21 (trisomy 21). That additional genetic material affects brain development, leading to varying degrees of intellectual disability along with distinctive facial features and sometimes other health considerations. Most cases result from nondisjunction during egg formation, and the likelihood increases with maternal age; there are also rare cases due to translocation or mosaicism.

The other options involve factors that are not genetic: fetal alcohol spectrum disorders come from alcohol exposure during pregnancy; meningitis is an infection that can affect the brain; lead poisoning is an environmental toxin that can impact development.