What genetic disorder is the single most important cause of mental retardation?
A) Autism spectrum disorder
B) Fragile-X syndrome
C) Down syndrome
D) Prader-Willi syndrome

Question

Quizplus · Accepted Answer

Down syndrome is the most common chromosomal disorder and a leading cause of intellectual disability. It occurs due to the presence of an extra copy of chromosome 21.

What Genetic Disorder Is the Single Most Important Cause of Mental