Autosomal Dominant Genetic Disorders
1 AnswerLearn Your Lipids answeredIf one parent has familial hypercholesterolemia (FH), there is a 50 percent chance that their son or daughter will also have it. Certain populations are known to have a higher prevalence of FH, particularly French Canadians and Dutch Afrikaners.
1 AnswerBrigham and Women's Hospital answeredAlthough we have two copies of our genes (the basic units of deoxyribonucleic acid (DNA) that provide instructions to our body), in autosomal dominant conditions a mutation in one copy of the gene is enough to cause a disease or susceptibility to a disease. A person who carries a mutation for an autosomal dominant condition has a 50% chance of passing the mutation on to his/her children. If a person does not carry a mutation, it is not possible to pass it on to the next generation. Dominant conditions affect both males and females.Helpful? 1 person found this helpful.
1 AnswerAllan Stewart, MD, Cardiothoracic Surgery, answered on behalf of Columbia University Department of Surgery
Loeys-Dietz syndrome (LDS) is a genetic disorder that shares similarities with Marfan syndrome. It affects proteins called transforming growth factor beta receptor 1 and 2, which are also part of the connective tissue found throughout the body. Some features of LDS overlap with Marfan syndrome, including aortic aneurysm or dissection, leakage of the mitral valve, loose flexible joints, and others.
Other features of LDS are unique, such as arteries that twist and wind, aneurysms in arteries other than the aorta, widely spaced eyes, cleft palate, wide or split uvula, heart defects including atrial septal defect, bicuspid aortic valve, and many other features. These patients have very unstable aortic tissue and should have a surgical evaluation as soon as the diagnosis of LDS is made.Helpful? 1 person found this helpful.
2 AnswersAllan Stewart, MD, Cardiothoracic Surgery, answered on behalf of Columbia University Department of Surgery
Connective tissue disorders significantly affect the aorta. The reason is because the aorta is essentially a tube that carries blood throughout the body. It is exposed to high shear stress. This pressure will ultimately expand the wall, if the structure (connective tissue) is abnormal. Think of it is a weakened piece of pipe. If the pressure in that pipe is high, the pipe will ultimately burst. It is not particularly different with the aorta.
The heart is a muscular organ with four chambers. The chambers fill with blood as the heart relaxes and eject or pump blood when the heart contracts. There are two atria and two ventricles. Veins carry blood from the body to the heart, while arteries carry blood away from the heart.
The heart also has four valves that separate the chambers and prevent blood from flowing backwards within the heart.
The sinuses of Valsalva lie directly above the aortic valve cusps, which open and close as the ventricle contracts and relaxes. There are three sinuses that correspond to the three individual cusps. In Marfan syndrome, the walls of the blood vessels become weak and stretch. When this occurs there is progressive enlargement of the sinuses of Valsalva and the ascending aorta. This causes the aorta to develop a pear-shaped appearance. This can lead to aneurysm (balloon) formation or aortic dissection, which is the tearing or separation of the layers of the aorta. These conditions can result in a medical emergency and can be life-threatening.
Aortic regurgitation (blood leaking back into the left ventricle) can also occur with Marfan’s. The aortic valve can become stretched and start leaking when the aortic root becomes dilated or stretched. The aortic root is where the aorta meets the aortic valve. Over time, this leakage can lead to stretching of the left ventricle. The left ventricle can become weak due to the increased amount of blood it has to pump out to the body. This leads to decreased pumping ability of the left ventricle over time and can lead to congestive heart failure.
The mitral valve also can be affected in people with Marfan syndrome. Mitral valve prolapse (MVP) occurs when the valve cusps become floppy and do not close tightly, allowing the cusps to bulge backward. This allows blood to leak backward into the left atrium. When the leakage is mild, there are not a lot of symptoms. As the leakage worsens, there is extra workload on the heart, which may cause symptoms of shortness of breath, palpitations and fatigue. When mitral valve prolapse progresses over time, the leakage of blood is referred to as mitral valve regurgitation.
There are tendons (chordae tendinae) that connect the papillary muscles to the mitral valve. They prevent the mitral valve from prolapsing into the left atrium. These tendons can rupture and lead to significant leakage of the mitral valve. This can potentially be a medical emergency and may require surgical intervention.
1 AnswerGenetic counseling should be performed prior to pregnancy as Marfan syndrome is an inherited condition (a condition that affects the body’s connective tissue). There is a 50% chance that your children will inherit the disease. Pregnancy also puts extra strain on the heart and aorta, and would put you in a high-risk category. Pregnancy may be contraindicated if you have increased aortic size, severe mitral regurgitation (backward flow of blood) or decreased heart muscle strength. Careful and frequent follow-up is essential to monitor blood pressure, as are monthly echocardiograms to watch for aortic enlargement or dissection. Bed rest may be required.
1 AnswerMarfan syndrome (a condition that affects the body’s connective tissue) may affect your daily life in a variety of ways.
Advances in medical care are helping people with Marfan syndrome lead longer and more enjoyable lives. Early diagnosis allows treatment to begin sooner. Your health care provider may recommend certain guidelines for daily living. Talk to your health care provider about what lifestyle changes can best help you.
For the most part, people with Marfan syndrome can lead a normal lifestyle. Most people with Marfan’s can do some type of physical and/or recreational activity. It is recommended that people with Marfan’s should avoid activities or jobs that require physically strenuous activity. You should not lift heavy weights if you have Marfan’s. Contact and competitive sports such as football and basketball should be avoided.
There are no special dietary restrictions for people with Marfan syndrome. It is recommended that you eat a well-balanced diet low in fat and cholesterol.
Having Marfan syndrome does not mean you cannot live a long and enjoyable life. It is recommended that you receive routine medical care and follow-ups. It is important that you seek care from a doctor who has experience in treating Marfan syndrome. It is also recommended that you have routine eye exams, dental care, cardiovascular care and skeletal exams. Your health care provider can help you determine the frequency of your visits.
1 AnswerSome patients with Marfan syndrome (a condition that affects the body’s connective tissue) may require heart surgery at some point in time. The most common types of surgery are:
Aortic aneurysm repair: The aorta is the largest artery in the body and is commonly affected by Marfan syndrome. The disease may weaken part of the aortic wall, resulting in a ballooning, or aneurysm, developing in that area. Surgery to repair the aneurysm is done with a special graft that replaces part of the aorta but leaves your natural valve in place. This procedure is called valve sparing. Your aortic valve may need to be repaired or replaced during this surgery.
Aortic valve replacement: As the aortic root becomes more dilated, the aortic valve may start to leak (regurgitation). When this occurs, the aortic valve may need to be repaired or replaced. This procedure may be done with or without repair of the aorta.
Mitral valve repair or replacement: People with Marfan syndrome may have mitral valve prolapse. This is a condition that occurs when the left ventricle contracts and mitral valve tissues bulge back into the left atrium, allowing blood to leak backward into the left atrium (mitral regurgitation). When this leakage becomes severe, mitral valve repair or replacement will be recommended.
1 AnswerThe medications generally used are to prevent or control complications related to Marfan syndrome (a condition that affects the body’s connective tissue). Beta-blockers are the most common type of medication used in people with Marfan’s. They are specifically utilized to slow the rate of progression of aortic dilatation. Angiotensin receptor blockers (ARB) have also been shown to prevent aortic enlargement and may be used to help treat hypertension as well as congestive heart failure. However, beta-blockers should still be the first line of treatment to prevent aortic complications.
1 AnswerWith genetic testing, a blood test is done that may help diagnose Marfan syndrome (a condition that affects the body’s connective tissue). The blood test is highly specialized and looks for the gene responsible for most cases of Marfan syndrome. The gene is called fibrillin-1, or FBN1. FBN1 is a large gene and more than 500 different mutations have been identified. Mutations seem to be unique to individual families. If a mutation is found in one family member, it is expected to be seen in other affected members of the family. The lab test is between 70% and 90% accurate and reliable for diagnosis.