Encyclopedia of Health and Medicine

M–N
Marfan syndrome A genetic disorder arising
from mutations in the fbn1 GENE that affect the
structure of connective tissues throughout the
body. The fbn1 gene encodes for fibrillin 1, a protein
molecule essential for the formation of
elastin. Elastin is the basis of the fibers that form
the connective tissues. In Marfan syndrome the
elastin is too soft, allowing connective tissues to
stretch more than normal. The INHERITANCE PATTERN
for Marfan syndrome is autosomal dominant,
meaning one parent who has the mutated gene
can pass the condition to his or her children. Marfan
syndrome primarily affects the cardiovascular
system, musculoskeletal system, and eyes.
Symptoms and Diagnostic Path
Marfan syndrome produces hallmark physical
characteristics that include
• tall, lanky frame with extraordinarily long arms
• elongated, narrow face
• crowded TEETH
• narrow, sunken chest
• long, thin fingers
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Many people who have Marfan syndrome have
severe MYOPIA (nearsightedness) and abnormalities
of the CORNEA. Within the body, one of the most
significant effects of Marfan syndrome is on the
major BLOOD vessels, notably the AORTA, and the
HEART valves. Because the connective tissue within
the walls of the arteries is softer than it should be,
the walls of the arteries are susceptible to separation
(ANEURYSM). As well, the heart valves are
often larger than normal and do not close properly,
allowing blood to backflow within the heart.
Mitral valve prolapse is the most common manifestation
of this aspect of Marfan syndrome. To
compensate, the heart intensifies the STRENGTH and
frequency of its contractions, which over time
enlarges the heart (CARDIOMYOPATHY).
There are no definitive diagnostic tests for Marfan
syndrome, and symptoms are sometimes mild
enough to escape detection until midlife or later
when cardiovascular problems begin to emerge.
An accumulation of symptoms points to the diagnosis,
particularly if there is a family history of
Marfan syndrome. The doctor may conduct
GENETIC TESTING for the fbn1 gene MUTATION to confirm
the diagnosis.
Treatment Options and Outlook
Treatment focuses on early detection of and therapy
for potential complications, notably CARDIO-
VASCULAR DISEASE (CVD). Doctors advise against
activities, especially competitive sports, that cause
rapid and extreme changes in BLOOD PRESSURE and
HEART RATE. Treatment may include medications to
maintain low blood pressure and heart rate as preventive
measures. Most people who have Marfan
syndrome should have an ECHOCARDIOGRAM (ULTRA-
SOUND examination of the heart) annually to
screen for changes in the heart’s size and valve
function and the stability of the aorta. Early surgery
to intervene when echocardiogram suggests a
dissecting aortal aneurysm can be lifesaving.
Risk Factors and Preventive Measures
Because cardiovascular complications of Marfan
syndrome can be severe or life threatening, doctors
recommend GENETIC COUNSELING for people
who have the disease. Marfan disease is preventable
only by preventing transmission of the
mutated bfn1 gene. For the 30 percent or so of
people in whom the mutation is spontaneous