URMC / Encyclopedia / Content Search Encyclopedia Single Gene Defects Many different single gene defects require clinical care by a doctor or other healthcare professional. Click on the links below to learn more about this topic. Autosomal Recessive: Cystic Fibrosis, Sickle Cell Anemia, Tay Sachs Disease X-linked Recessive: Red-Green Color Blindness, Hemophilia A X-linked Dominant: Incontinentia Pigmenti