There are many genetically transmitted diseases. According to Elizabeth Corwin, PhD, author of "Handbook of Pathophysiology," approximately 4,500 diseases are due to single-gene disorders alone. Single-gene disorders are diseases which are a result of a mistake made in one gene. In addition to the single-gene disorders, there are the genetically transmitted diseases which are a result of mistakes caused by several genes.
Huntington's Disease
This hereditary disease is the result of a gene abnormality on chromosome 4, where too much of a specific genetic code has been repeated. As explained by David Eidelberg, M.D., Professor of Neurology and Neurosurgery at NYU School of Medicine, not only is Huntington's genetically transmitted, but the amount of the repeat code on chromosome 4 can increase from generation to generation. As a result, the disease can either start earlier in the next generation or it can be more severe. The symptoms usually start between the ages of 30 and 50 years. Persons with Huntington's gradually develop writhing muscular movements, a change in behavior, irritability, antisocial behavior, dementia and then depression. No cure has been discovered. The disease gets progressively worse over time, and persons with Huntington's disease have a life expectancy of about 20 years from the time of the initial diagnosis.
Autosomal Dominant Polycystic Kidney Disease
According to Suzanne Watnick, M.D., Associate Professor of Medicine at the Oregon Health and Science University, this genetic disease is relatively common, affecting approximately 500,000 people. In this disorder, large cysts develop in both kidneys, causing them to enlarge. Persons with polycystic kidney disease will usually have (flank) pain in the area of the kidneys, hypertension, blood in your urine (hematuria) and anemia. They also have a 50% chance of developing kidney failure by the age of 60 years.
Marfan Syndrome
Marfan syndrome is a genetically transmitted disease in which a gene mutation leads to abnormalities in the skeletal and cardiovascular systems as well as in the eyes. Persons with Marfan syndrome are tall, with very long arms and fingers, and very flexible joints. The aortic artery in the heart can be abnormal, putting affected persons at risk for developing an aortic aneurysm. They may also have problems with their eyes, because the lens is not in their proper position due to the syndrome.
Hemophilia
Hemophilia A is a hereditary disease that affects only males. It is caused by a decreased amount of a substance called factor 8, which is needed for blood to clot. Hemophilia B is likewise a hereditary disease that only affects males. But in hemophilia B, there is a decreased amount of factor 9, another substance needed for blood to be able to clot. Persons with either type of hemophilia, however, bleed excessively from only a small amount of trauma or even from minor dental procedures. They can easily develop internal bleeding, including in the head, skin and organs, and can have painful joints caused by bleeding within the joints.
Alport's Syndrome
This is another hereditary disease that only affects males. In this disorder, men will have an inflammation in the capillaries within their kidneys, which is referred to as glomerulonephritis. They will also eventually see blood in their urine (hematuria), have various eye abnormalities and become deaf.
References
- "Current Medical Diagnosis & Treatment 2009"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2009
- "Handbook of Pathophysiology"; Elizabeth Corwin, MSN, PhD, FNP; 2000
- The Merck Manual: Huntington's Disease
