About Marfan Syndrome
Marfan syndrome
is a progressive genetic disorder that affects the body's connective tissue.
Connective tissue is everywhere in the body, providing structure and support
for cells. Think of it as a sort of "glue" that helps support every
organ, blood vessel, bone, joint, and muscle.
In people with
Marfan syndrome, this "glue" is weaker than normal because of a
defect in the body's production of the protein fibrillin, a major component of
connective tissue. Weakened connective tissue can lead to problems in many parts
of the body, especially the heart, eyes, and bones.
Even though the
disease has no cure, the good news is that doctors can successfully treat just
about all of its symptoms. Just a few decades ago, most people with Marfan
syndrome didn't live past 40. Now, thanks to new research and treatments, those
who are diagnosed early and get good medical care have just about the same
lifespan as everyone else.
Current
research on a group of medications called ACE inhibitors appears extremely
promising and is likely to further improve the health of people with Marfan
syndrome.
Causes
Marfan syndrome
is pretty rare, affecting about 1 in every 5,000 people. Researchers have
traced the disorder to a defect in a gene found on chromosome 15. It's this
mutation (change) that causes the abnormality in the production or the
structure of fibrillin.
About 75% of
the time, the gene for Marfan syndrome runs in families, getting passed down to
kids from parents who have the disease. The gene is autosomal dominant, which
means every child born to a parent who has Marfan syndrome has a 50% chance of
having it too.
In the
remaining 25% of cases, though, neither parent has the disease; the genetic
mutation responsible for Marfan syndrome occurs spontaneously in either the egg
or sperm cell at the time of conception. No one knows what causes this
mutation, but those born with it have a 50% chance of passing it on to their
kids.
Although people
with Marfan syndrome often have similar physical features, the disease doesn't
affect everyone in the same way. Some have very mild symptoms, while others
have severe ones — even within the same family. This is known as "variable
expression," and it makes it almost impossible to predict how the disease
will progress in any affected individual.
Signs and Symptoms
People with
Marfan syndrome are often (but not always) much taller than their family
members and peers and have a lean, lanky build. Their fingers and toes are
usually long and thin, and their joints are loose. Their arms and legs are often
disproportionately long when compared with their torso, and their arm span is
often a lot greater than their height.
They may share
some facial characteristics, too, including a long, thin face; deep-set eyes; a
small jaw; a high, arched roof of the mouth; and crowded teeth.
Complications
People with
Marfan syndrome are also susceptible to complications in the following body
systems:
Heart and Blood Vessels
The most serious
complication of Marfan syndrome involves theheart. Over time, the disorder
can cause the aorta — the large artery that carries blood away from the heart
to the body — to stretch and dilate (widen).
If undetected
or untreated, the wall of the aorta can eventually begin to tear and separate,
allowing blood to leak through (this is known as an aortic dissection). A large, sudden rupture can be fatal.
Problems with
the heart valves are common too. Instead of closing tightly, valves (usually
the mitral and/or aortic valves) may become large and floppy, allowing blood to
leak backwards through the heart. A minor leak may cause few symptoms, but a
large one can cause shortness of breath and an irregular heartbeat, as well as
a heart murmur. Leaky heart valves cause the heart to work harder and become
enlarged, so they must be carefully monitored.
Eyes
More than half
of all people with Marfan syndrome have a condition known as "dislocated
lenses." That means the lenses of the eye, which are usually centered
behind the pupil and held in place with connective tissue, may shift up, down,
or to the side. Vision problems may occur depending on the position of the
lens. The vision problems may require glasses at first, and later may require
surgery.
People with
Marfan syndrome also often have myopia (nearsightedness), and they are at
greater risk for developing other problems — like detached retinas (when the
light-sensing tissue at the back of the eye comes loose), glaucoma (high
pressure in the eye), or cataracts (cloudy lenses) — earlier in life than other
people. Young children are especially prone to developing amblyopia (lazy eye).
Skeletal Problems
In addition to excessive
height and long limbs, Marfan syndrome may cause other skeletal problems, such
as scoliosis (curvature of the
spine) and chest wall abnormalities (the chest bone may either curve in or
protrude out, giving the chest a sunken-in or a pigeon-breasted appearance).
Overly loose joints and flat feet are common.
Other symptoms
may affect the skin, nervous system, and lungs, but these tend to be less
common and less serious, especially in kids and teens.
Diagnosing Marfan Syndrome
There's no
single test for diagnosing Marfan syndrome. Diagnosis depends on detailed exams
by a team of doctors, including a geneticist (a doctor who specializes in
inherited disorders), a cardiologist (heart specialist), ophthalmologist (eye
doctor), and an orthopedist (bone specialist). Molecular testing for a mutation
in the FBN1 gene is part of the comprehensive evaluation.
First, a
geneticist will ask about any family history of the disorder or whether any
relatives died early from heart-related deaths. He or she may also take
detailed skeletal measurements. The geneticist may order mutation testing on a
small blood sample.
A cardiologist
may listen for a heart murmur and will likely perform tests such as:
·
a chest X-ray
·
an echocardiogram, which uses sound waves to
produce a picture of the heart to check the size of the aorta and the
functioning of the valves
An
ophthalmologist may perform a "slit lamp" test (a slit lamp allows
the doctor to see the front of the eye under high magnification) while the eyes
are dilated to check for lens dislocation and any other abnormalities.
An orthopedist
will check for curvatures of the spine and chest bone, as well as joint
problems and flat feet.
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