Which of the following genetic disorders is caused by the presence of an extra copy of chromosome 21?
A)Down syndrome
B)Turner syndrome
C)Sickle-cell anemia
D)Phenylketonuria

Question

Quizplus · Accepted Answer

Down syndrome, also known as trisomy 21, occurs when there is an extra copy of chromosome 21. This leads to developmental and intellectual disabilities, distinctive facial features, and other health issues. Turner syndrome is caused by a missing or incomplete X chromosome, sickle-cell anemia is caused by a mutation in a single gene, and phenylketonuria is also caused by a mutation in a single gene.

Which of the Following Genetic Disorders Is Caused by the Presence