A hypochondriac could spend many a sleepless night browsing the Internet for information on terrible, deadly, bizarre or otherwise disturbing diseases. The complexity of the human body seems to be matched only by the number of things that can go wrong with it.
In this article, we'll take a look at 10 of the most serious hereditary conditions -- diseases that are unavoidable for those who get them because they're encoded in the genome. Some are well known, some are not; some are fatal, others can be treated. All affirm that we human beings are immensely complicated organisms whose dysfunctions we are only beginning to understand.
Cystic fibrosis used to be a disease that caused death by the time a patient was out of high school. That's no longer the case -- some patients now live 40 or more years -- but it's still a difficult, debilitating disease that begins with breathing problems and can later lead to complications in other parts of the body.
The main culprit in cystic fibrosis is a defective gene that causes mucus and other bodily fluids to be far more viscous than they should be. Essentially, these abnormally thick fluids gum up the body's works, clogging up passageways in the pancreas and lungs. A range of problems can follow, including repeated respiratory infections, trouble breathing, severe digestive problems (in turn preventing weight gain and normal growth), diabetes and liver failure.
While there's no cure for cystic fibrosis, some of its symptoms and associated conditions can be treated. Some patients may use inhalers to take drugs that open bronchial passageways or turn to mucus-thinning medications.
9: Huntington's Disease
Huntington's disease is an incurable genetic disorder that causes the brain's nerve cells to progressively and irreparably break down. The culprit is a mutated gene on the patient's fourth chromosome. Essentially, the defective gene causes a piece of DNA to be duplicated many more times than it should [source: MedlinePlus].
Most cases of the disease appear in a patient's 30s or 40s, although it may develop even before adulthood. The disease's early symptoms are characterized by diminished motor function (including clumsiness and lack of coordination) and a range of cognitive problems. A patient may also be subject to sudden mood changes, becoming irritable or depressed. As the disease progresses, the patient may exhibit dementia, involuntary spasms, difficulty speaking and swallowing, stress and paranoia.
Children of people with Huntington's disease have a 50 percent chance of inheriting the defective gene. As the gene is passed down to later generations, the defective section of DNA is duplicated more and more, which in turn causes the disease to develop at a progressively younger age [source: MedlinePlus].
Unfortunately, there's no cure or effective treatment for Huntington's disease. Patients progressively become sicker, often dying from some complication or secondary illness.
8: Hemophilia
Hemophilia is actually a group of disorders -- hemophilia A, hemophilia B and hemophilia C -- that make it difficult for a person's blood to clot. Each of the three disorders is linked to a lack of a specific clotting factor. In a healthy person, a number of clotting factors, or proteins, work together to stop bleeding when a blood vessel is broken. Someone with hemophilia lacks the associated clotting factor -- factor VIII in the case of hemophilia A, factor IX for hemophilia B and factor XI for hemophilia C [source: Mayo Clinic].
Symptoms of hemophilia include prolonged bleeding (in disproportion to the severity of the injury), vicious bruising, nosebleeds and joint pain. The severity of the condition varies depending on the type and on the person's overall health. It's the sort of chronic condition that can be very dangerous, even deadly, but can also be managed. However, patients with serious hemophilia may find themselves frequently going to the hospital in order to receive blood and plasma transfusions, or to receive injections of hormones that spur the release of a clotting factor.
7: Sickle Cell Disease
Sickle cell disease, also known as sickle cell anemia, is a disorder named as such because a patient's red blood cells sometimes form a tough, sickle-like shape, which can cause them to get stuck in blood vessels. Healthy blood cells are softer and round, allowing them to travel easily through blood vessels. Sickle cells are also weaker than healthy red blood cells, so they have a tendency to break down quickly -- their life span is up to 90 percent shorter than that of normal red blood cells [source: Mayo Clinic].
The disease is caused by a mutation in the gene that contains the instructions for creating hemoglobin. While it is inherited from the parents, both parents must pass on a copy of the mutated gene for the disease to develop in a child.
Sickle cell disease can cause a number of serious health problems, especially if left unchecked, including hypertension, stroke, blindness and potentially fatal organ damage. Generally, it's a condition that's managed with a healthy lifestyle, use of dietary supplements and carefully monitoring of any complications so they can be dealt with immediately. Children are often given penicillin for several years, beginning in infancy, in order to stave off infections.
6: Neurofibromatosis
Neurofibromatosis is a group of genetic disorders characterized by the growth of tumors throughout the nervous system. There are actually three types of the disease -- neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2) and Schwannomatosis -- although NF1 is the most common. NF1 is caused by a defective gene on chromosome 17, and NF2 is caused by a defective gene on chromosome 22. However, the cause of Schwannomatosis remains unknown. In all three cases, it appears that the defective gene prevents essential proteins from being produced, which leads to uncontrolled cell division [source: Mayo Clinic].
Because the tumors can appear anywhere in the nervous system -- from the spinal cord to the extremities -- the effects of neurofibromatosis can vary significantly between patients. The disease is not usually fatal, but it can lead to a number of severe complications, such as cognitive impairment, bone deformities, hearing loss or even cancer.
There's no cure for neurofibromatosis. Surgeons may remove tumors in order to ease pain and reduce pressure on organs or nerves, although tumors can grow back after being removed.
5: Tay-Sachs Disease
Tay-Sachs disease is a serious genetic disorder that leads to the destruction of a child's neurons, eventually ending in death -- often by age 4. The culprit is a faulty gene on the 15th chromosome that prevents the body from producing a protein called hexosaminidase A, which in turn leads to the buildup of gangliosides. When the body can't get rid of gangliosides, these chemicals accumulate to levels that are very harmful for neurons [source: National Institute of Neurological Disorders and Stroke].
Symptoms of Tay-Sachs -- which can be diagnosed in utero -- often develop a few months into life. A Tay-Sachs child suffers a decline (and lack of development) of motor skills, loss of senses, severe cognitive impairment, paralysis and, finally, death.
As of yet, there's no cure for Tay-Sachs, although genetic screening can let prospective parents know if they're carriers. A child must inherit the Tay-Sachs gene from both parents in order to develop the disease.
4: Angelman Syndrome
Described in 1965 by Dr. Harry Angelman, Angelman syndrome is a disorder characterized by serious developmental delay and nervous system problems. Symptoms usually appear within the first few months of a child's life, often because he or she is having problems eating. Around age 2, a child will start experiencing seizures and will show little sign of being able to speak. As they develop, patients with Angelman syndrome generally exhibit diminished motor skills, hyperactivity, a smaller than normal head and sleep disorders.
Unlike many of the disorders discussed here, Angelman syndrome is not fatal, although there's no treatment. Even so, a number of therapies exist that can help patients become more functional and live better lives. While communication can be very difficult, some people with Angelman syndrome manage to learn sign language or express themselves through nonverbal communication. They may also live as long as those who don't have the disorder [source: Genetics Home Reference].
People with Angelman syndrome are also known to laugh and smile frequently, often without prompting. The source of these happy expressions remains unknown [source: Angelman Syndrome Foundation Inc.].
3: Polycystic Kidney Disease
Polycystic kidney disease, or PKD, is a genetic disorder that causes numerous noncancerous cysts to develop on a patient's kidneys. While the cysts themselves are benign, they can lead to a number of complications -- anything from kidney stones or kidney failure to high blood pressure or abdominal pain. Some patients go years without being diagnosed and consequently find themselves in the doctor's office with a kidney weighing 20 to 30 pounds (9 to 14 kilograms) [source: Mayo Clinic].
2: Canavan Disease
One of several hereditary disorders commonly associated with Ashkenazi Jews, who it affects in greater numbers than other populations, Canavan disease is a degenerative condition that leads to death [source: MedlinePlus]. Its main effect is to prevent the production of an enzyme called aspartoacylase, which is supposed to prevent the excessive accumulation of a certain acid; without enough aspartoacylase, acid accumulates, eroding brain matter.
This kind of brain erosion is very serious, and symptoms often appear before a child's first birthday [source: MedlinePlus]. A parent might notice that the child has difficulty controlling his or her head and hasn't developed normal muscle strength. Other symptoms may include difficulty eating, seizures and a growing head because of intracranial pressure.
Unfortunately, the prognosis for Canavan is very grim, although the disease can be detected through prenatal testing. But if born with the condition, a child may die within a year and a half, after having quickly become severely disabled.
1: Muscular Dystrophy
The term muscular dystrophy actually encompasses many different muscle diseases that vary in severity and time of onset. However, in general, they share the following feature: Muscles are easily damaged and become weaker over time.
Some types of muscular dystrophy only affect voluntary muscles -- that is, muscles you deliberately use, like your biceps -- while others can affect involuntary muscles, like the heart. Some variations of the disease are also localized to specific muscle groups. The type of muscular dystrophy a person has depends on the specific gene suffering from a mutation.
There's no cure for muscular dystrophy. Patients often pursue regular physical therapy and an active lifestyle -- to whatever extent possible -- in order to counteract the disease's wasting effects. Still, a patient may suffer from falls, diminished motor skills and other complications that will leave him or her in need of a wheelchair or professional care [sources: Mayo Clinic, MedlinePlus].
For more information about hereditary conditions, genetic disorders and other related topics, click to the next page.
Because muscular dystrophy causes weakened muscles, many people with the disease are in wheelchairs.
Image Credit: Kevin Winter/Getty Images
A.D.A.M. "Tay-Sachs Disease." The New York Times. Oct. 21, 2008. (Oct. 11, 2010) http://health.nytimes.com/health/guides/disease/tay-sachs-disease/overview.html
Angelman Syndrome Foundation Inc. "Laughter and Happiness." (Oct. 11, 2010) http://www.angelman.org/stay-informed/facts-about-angelman-syndrome---7th-edition/behavioral-and-developmental-issues/laughter-and-happiness/
Canavan Foundation. "What is Canavan disease?" (Oct. 11, 2010) http://www.canavanfoundation.org/canavan.php
Genetics Home Reference. "Tay-Sachs disease." National Institutes of Health. Oct. 3, 2010. (Oct. 11, 2010) http://ghr.nlm.nih.gov/condition/tay-sachs-disease
Genetics Home Reference. "Angelman syndrome." National Institutes of Health. July 2009. (Oct. 11, 2010) http://ghr.nlm.nih.gov/condition/angelman-syndrome
Mayo Clinic. "Cystic fibrosis." March 2, 2010. (Oct. 11, 2010) http://www.mayoclinic.com/health/cystic-fibrosis/DS00287/METHOD=print
Mayo Clinic. "Hemophilia." May 16, 2009. (Oct. 11, 2010) http://www.mayoclinic.com/health/hemophilia/DS00218/METHOD=print
Mayo Clinic. "Huntington's disease." May 8, 2009. (Oct. 11, 2010) http://www.mayoclinic.com/health/huntingtons-disease/DS00401/METHOD=print
Mayo Clinic. "Neurofibromatosis." July 1, 2010. (Oct. 11, 2010) http://www.mayoclinic.com/health/neurofibromatosis/DS01185/METHOD=print
Mayo Clinic. "Polycystic kidney disease." July 2, 2009. (Oct. 11, 2010) http://www.mayoclinic.com/health/polycystic-kidney-disease/DS00245/METHOD=print
Mayo Clinic. "Sickle cell anemia." April 1, 2009. (Oct. 11, 2010) http://www.mayoclinic.com/health/sickle-cell-anemia/DS00324/METHOD=print
MedlinePlus. "Canavan disease." National Institutes of Health. Oct. 14, 2009. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/001586.htm
MedlinePlus. "Cystic fibrosis." National Institutes of Health. July 7, 2010. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000107.htm
MedlinePlus. "Hemophilia." National Institutes of Health. March 2, 2009. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000537.htm
MedlinePlus. "Hemophilia A." National Institutes of Health. March 28, 2010. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000538.htm
MedlinePlus. "Hemophilia B." National Institutes of Health. March 28, 2010. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000539.htm
MedlinePlus. "Huntington's disease." National Institutes of Health. June 24, 2009. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000770.htm
MedlinePlus. "Muscular dystrophy." National Institutes of Health. March 9, 2010. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/001190.htm
MedlinePlus. "Polycystic kidney disease." National Institutes of Health. Aug. 13, 2009. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000502.htm
MedlinePlus. "Von Willebrand disease." National Institutes of Health. March 28, 2010. (Oct. 11, 2010) http://www.nlm.nih.gov/medlineplus/ency/article/000544.htm
National Heart Lung and Blood Institute. "What Is von Willebrand Disease." National Institutes of Health. May 2009. (Oct. 11, 2010) http://www.nhlbi.nih.gov/health/dci/Diseases/vWD/vWD_WhatIs.html
National Hemophilia Foundation. "Factor XI Deficiency." (Oct. 11, 2010) http://www.hemophilia.org/NHFWeb/MainPgs/MainNHF.aspx?menuid=189&contentid=54&rptname=bleeding
National Institute of Neurological Disorders and Stroke. "NINDS Tay-Sachs Disease Information Page." National Institutes of Health. Feb. 14, 2007. (Oct. 11, 2010) http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm
National Institute of Neurological Disorders and Stroke. "NINDS Angelman Syndrome Information Page." National Institutes of Health. Feb. 8, 2007. (Oct. 11, 2010) http://www.ninds.nih.gov/disorders/angelman/angelman.htm
National Institute of Neurological Disorders and Stroke. "Neurofibromatosis Fact Sheet." National Institutes of Health. May 6, 2010. (Oct. 11, 2010) http://www.ninds.nih.gov/disorders/neurofibromatosis/detail_neurofibromatosis.htm
National Institute of Neurological Disorders and Stroke. "NINDS Neurofibromatosis Information Page." National Institutes of Health. May 6, 2010. (Oct. 11, 2010) http://www.ninds.nih.gov/disorders/neurofibromatosis/neurofibromatosis.htm
Sickle Cell Disease Association of America. "What is Sickle Cell Disease (SCD)?" (Oct. 11, 2010) http://www.sicklecelldisease.org/index.cfm?page=about-scd
When you're surrounded by cubicles and concrete, it's easy to forget that we live on a planet packed full of breathtaking natural beauty, so take a trip with us as we explore 10 of the very best the Earth has to offer.
From The Beatles on The Ed Sullivan Show to the latest breaking news, TV makes more memories than there are viewers. Here are 10 of the most talked-about broadcasts in television history.
Comments ( )