In which of the following forms of Down syndrome does the extra copy of one of the chromosome pairs interfere with the normal development of the body and brain?
A) Fragile X syndrome
B) Trisomy 21
C) Tay-Sachs disease
D) PKU

Question

Quizplus · Accepted Answer

Trisomy 21, also known as Down syndrome, occurs when there is an extra copy of chromosome 21. This interferes with the normal development of the body and brain, leading to characteristic physical and intellectual features. Fragile X syndrome, Tay-Sachs disease, and PKU are all genetic disorders, but they involve specific mutations or deficiencies rather than an extra chromosome.

In Which of the Following Forms of Down Syndrome Does