Inherited genetic diseases are passed on by either one parent--as in the case of autosomal dominant diseases, in which only one copy of the gene need be present for a person to have a disorder--or by both parents. In recessive genetic diseases, both parents must pass a copy of the abnormal gene to an offspring for the disease to be present. Recessive disorders are more common because people who carry the genes and pass them on are not ill with the disease themselves.
Cystic Fibrosis
Cystic fibrosis is the most common inherited genetic disease in the United States; one in 29 people carries one copy of the gene, the University of Maryland Medical Center states. People with cystic fibrosis produce thick mucus that accumulates in the lungs, interfering with breathing, and in the pancreas, interfering with digestion. Low oxygen levels, frequent lung infections and failure to grow are symptoms of cystic fibrosis. There's no cure for cystic fibrosis, but taking enzymes that help with digestion keeps people with the disease from becoming malnourished, and breathing treatments and physical therapy decrease lung damage. Antibiotics are given to prevent lung infections.
Sickled Cells
Sickle cell anemia is a disease of the red blood cells most commonly found in African-Americans and those with Mediterranean or Middle Eastern ancestry. Sickle cell anemia is a recessive disorder, which means both parents must pass the gene for the child to have the disease. Sickle cell anemia destroys red blood cells by changing their shape; sickled cells live only 10 to 20 days, as opposed to 120 days for normal red blood cells, the Mayo Clinic states.
Symptoms of the disease are anemia, pain from the sickled cells blocking blood flow through blood vessels, low oxygen levels and retinal eye damage. There's no cure for sickle cell anemia; treatments include medications to stimulate fetal hemoglobin cells, cells that prevent sickle cells from development, pain medications, blood transfusions and antibiotics to decrease the risk of infection.
Tay-Sachs Disease
Tay-Sachs disease is a recessive genetic disorder found mostly in Ashkenazi Jews, Jewish people from Middle and Eatern Europe, but also in other populations. One in 27 Ashkenazi Jews carries the gene. Tay-Sachs is the absence of an enzyme, Hexosaminidase A (Hex A), that breaks down fatty proteins that interfere with growth and development. Children with Tay-Sachs have normal development until 3 to 6 months and then start to lose the ability to see, hear or move. Most children with Tay-Sachs die before age 5.
