<prompt> For a normal husband and wife the first child was diagnosed to have cystic fibrosis. What is the percentage of chances for the second child be affected -2550075  <response>: Ans. is c i.e., 0 o Cystic fibrosis is an autosomal recessive disorder. o If husband and wife are clinically normal and the child has developed the disease that means both husband wife are carrier. o 25 will be affected and 75 will be phenotypically normal. o If one child is already affected, the chance for the disease in the second offspring is zero. 