I thin the nurse knows that Whites have the highest incidence of cystic fibrosis. Whites have the highest incidence of cystic fibrosis . Cystic Fibrosis is a disease in which a mutated gene causes a thick and sticky mucus to be produced, resulting in mucus build up in the lungs and digestive tract. Before puberty, boys are affected more with asthma than girls. Female African Americans have the highest mortality rates for Asthma than all ethnic/gender groups. Whites on the other hand have the highest incidence of (COPD), even though higher rates of smoking occur in other ethnic groups..