M–N

Marfan syndrome A genetic disorder arising
from mutations in the fbn1GENEthat affect the
structure of connective tissues throughout the
body. The fbn1gene encodes for fibrillin 1, a pro-
tein 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. Mar-
fan 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

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 BLOODvessels, notably the AORTA, and the
HEARTvalves. Because the connective tissue within
the walls of the arteries is softer than it should be,
the walls of the arteries are susceptible to separa-
tion (ANEURYSM). As well, the heart valves are
often larger than normal and do not close prop-
erly, allowing blood to backflow within the heart.
Mitral valve prolapse is the most common mani-

festation of this aspect of Marfan syndrome. To

compensate, the heart intensifies the STRENGTHand

frequency of its contractions, which over time

enlarges the heart (CARDIOMYOPATHY).

There are no definitive diagnostic tests for Mar-

fan 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 diag-

nosis, particularly if there is a family history of

Marfan syndrome. The doctor may conduct

GENETIC TESTINGfor the fbn1gene MUTATIONto con-

firm the diagnosis.

Treatment Options and Outlook

Treatment focuses on early detection of and ther-

apy for potential complications, notably CARDIO-

VASCULAR DISEASE (CVD). Doctors advise against

activities, especially competitive sports, that cause

rapid and extreme changes in BLOOD PRESSUREand

HEART RATE. Treatment may include medications to

maintain low blood pressure and heart rate as pre-

ventive 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 sur-

gery 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, doc-

tors recommend GENETIC COUNSELING for people

who have the disease. Marfan disease is preventa-

ble only by preventing transmission of the

mutated bfn1gene. For the 30 percent or so of

people in whom the mutation is spontaneous

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