Question

which condition involves an extra chromosome?
o a. huntingtons disease
o b. phenylketonuria
o c. down syndrome
o d. sickle-cell disease

Explanation:

• Huntington's disease is caused by a mutation in the HTT gene on chromosome 4.
• Phenylketonuria is due to a mutation in the PAH gene on chromosome 12.
• Sickle - cell disease is caused by a mutation in the HBB gene on chromosome 11.
• Down syndrome is typically caused by an extra copy of chromosome 21 (trisomy 21).

Answer:

C. Down syndrome