Human disorders attributable to a single pair of recessive genes

trait conspicuous signs

albinism lack of pigment in skin, hair, and eyes, with significant visual problems

Tay-Sachs disease listlessness, seizures, blindness, death in early childhood

cystic fibrosis chronic lung and intestinal symptoms

phenylketonuria light pigmentation, mental retardation, seizures

thalassemia mild or severe anemia, enlarged spleen and liver, stunted growth, bone deformation

sickle cell anemia fatigue, shortness of breath, delayed growth, muscle and abdominal pain