Marfan syndrome
Marfan syndrome: Excerpt from Professional Guide to Diseases (Eighth Edition)
Marfan syndrome is a rare, inherited, degenerative, generalized disease of the connective tissue that causes ocular, skeletal, and cardiovascular anomalies. It probably results from elastin and collagen abnormalities. Death is usually attributed to cardiovascular complications and may occur any time from early infancy to adulthood, depending on the severity of the symptoms. Marfan syndrome affects males and females equally.
Causes
Marfan syndrome is inherited as an autosomal dominant trait of chromosome 15. It's caused by mutations in gene fibrillin-1, producing changes in elastic tissues, especially of the aorta, eye, and skin. Mutations of fibrillin-1 also cause overgrowth of long bones. In 85% of patients with this disease, the family history confirms Marfan syndrome in one parent as well. In the remaining 15%, a negative family history suggests a fresh mutation, possibly from advanced paternal age.
Signs and symptoms
The most common signs and symptoms of this disorder are skeletal abnormalities, particularly excessively long tubular bones and an arm span that exceeds the patient's height. The patient is usually taller than average for his family (in the 95th percentile for his age), with the upper half of his body shorter than average and the lower half, longer. His fingers are long and slender (arachnodactyly). Weakness of ligaments, tendons, and joint capsules results in joints that are loose, hyperextensible, and habitually dislocated. Excessive growth of the rib bones gives rise to chest deformities such as pectus excavatum (funnel chest).
Eye problems are also common; 75% of patients have crystalline lens displacement (ectopia lentis), the ocular hallmark of Marfan syndrome. Quivering of the iris with eye movement (iridodonesis) typically suggests this disorder. Most patients are severely myopic, many have retinal detachment, and some have glaucoma.
The most serious complications occur in the cardiovascular system and include weakness of the aortic media, which leads to progressive dilation or dissecting aneurysm of the ascending aorta. Such dilation appears first in the coronary sinuses and is commonly preceded by aortic insufficiency. Less-common cardiovascular complications include mitral valve prolapse and endocarditis.
Other associated problems include sparsity of subcutaneous fat, frequent hernias, cystic lung disease, recurrent spontaneous pneumothorax, and scoliosis or kyphosis.
Diagnosis
Because no specific test confirms Marfan syndrome, diagnosis is based on typical clinical features (particularly skeletal deformities and ectopia lentis) and a history of the disease in close relatives. Useful supplementary procedures, though not definitive for diagnosis, include X-rays for skeletal abnormalities and an echocardiogram to detect aortic root dilation.
Treatment
Attempts to stop the degenerative process have met with little success. Therefore, treatment of Marfan syndrome is basically aimed at relieving symptoms — for example, surgical repair of aneurysms and ocular deformities. In young patients with early dilation of the aorta, prompt treatment with beta-adrenergic blockers may decrease ventricular ejection and protect the aorta; extreme dilation requires surgical replacement of the aorta and the aortic valve. Steroids and sex hormones have been successful (especially in girls) in inducing precocious puberty and early epiphyseal closure to prevent abnormal adult height. Genetic counseling is important, particularly because pregnancy and resultant increased cardiovascular workload can produce aortic rupture.
Special considerations
❑ High school and college athletes (particularly basketball players) who fit the criteria for Marfan syndrome should undergo a careful clinical and cardiac examination before being allowed to play, to avoid sudden death due to dissecting aortic aneurysm or other cardiac complications.
❑ Provide the patient with supportive care, as appropriate for his clinical status.
❑ Educate the patient and his family about the course of the disease and its potential complications.
❑ Stress the need for frequent checkups to detect and treat degenerative changes early.
❑ Emphasize the importance of taking prescribed medications as ordered and of avoiding contact sports and isometric exercise.
Pediatric tip
To encourage normal adolescent development, advise the parents to avoid unrealistic expectations for their child simply because he's tall and looks older than his years.
❑ Refer the patient and family to the National Marfan Foundation for additional information.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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- LORDOSIS
- "Differential Diagnosis in Primary Care" (2007)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Scoliosis (Professional Guide to Diseases (Eighth Edition))
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