Which of the following is NOT a disease that is caused by recessive genes?
A) PKU
B) Down syndrome
C) Cystic fibrosis
D) Tay-Sachs disorder

Question

Which of the following is NOT a disease that is caused by recessive genes?
A) PKU
B) Down syndrome 
C) Cystic fibrosis 
D) Tay-Sachs disorder

Quizplus · Accepted Answer

Down syndrome is not caused by a recessive gene. It is caused by a trisomy (an extra copy) of chromosome 21, which can be either inherited from the mother or the result of a spontaneous genetic mutation. PKU, cystic fibrosis, and Tay-Sachs disorder are all caused by recessive gene mutations.

Which of the Following Is NOT a Disease That Is