Marfan
Syndrome
Marfan
syndrome is a disorder involving the body's connective
tissue. Connective tissue has many important functions,
including the following:
- assisting with growth
and development of the body's cells, both before
and after birth
- supporting tissues
in the body
- acting as an adhesive
to hold certain tissues together
- protecting joints
- facilitating the passage
of light through the eye
A defective
(FBN1) gene associated with Marfan syndrome affects
the formation of a protein in connective tissue
called fibrillin, which impacts the integrity
of many organs and structures in the body. Organs
and body systems that can be impacted include,
but are not limited to, the following:
- heart and major blood
vessels
- lungs
- skeletal system
- spinal cord
- eyes
- skin
According
to the March of Dimes, at least one in 5,000 people
in the US have Marfan syndrome. Marfan syndrome
occurs in equal numbers in males and females,
and also appears equally in all races and ethnic
groups.
Marfan
syndrome is caused by an abnormality (or mutation)
in one specific gene (FBN1). Up to 75 percent
of the time, this mutated gene is inherited from
a parent who is affected.
Nearly
25 percent of the time, cases are thought to be
caused by new mutations in the family (not inherited
from a parent). Scientists have noted that offspring
of fathers who are older (than the norm) at the
time of conception may be affected by this gene
mutation more often than others. Mutations occur
sporadically (by chance) in the sperm of older
men (over 45 years) who father children at a rate
of 1 percent. These "point mutations" can result
in Marfan syndrome, or other disorders, depending
on which gene is accidentally altered.
Marfan
syndrome is an autosomal dominant disorder. This
means that each offspring of an affected parent
will have a 50 percent chance of also being born
with the disorder. Similarly, when a child is
born with Marfan syndrome to unaffected parents,
the child will have a 50 percent risk of passing
the gene on to the next generation.
Children
with Marfan syndrome are at risk for serious problems
involving the cardiovascular system, including
the following:
- mitral valve prolapse
- an abnormality of the valve between
the left atrium and left ventricle of the heart
that causes backward flow of blood from the
left ventricle into the left atrium.
- arrhythmia (or dysrhythmia)
- a fast, slow, or irregular heartbeat.
- aortic regurgitation
- backwards leakage of blood from
the aorta, through a weakened aortic valve,
and into the left ventricle, resulting in stress
in the left heart and inadequate blood flow
to the body.
- aortic dissection
- weakening of the layers inside
the aorta, which can result in tears in the
aortic wall and leakage of blood into the chest
or abdomen; a medical emergency.
A deficiency
of fibrillin in connective tissue creates the
abnormalities in organs and body structures that
may be seen with Marfan syndrome. An extensive
list of abnormalities can occur with the disorder;
only symptoms listed as "major criteria" are listed
below. Other symptoms may be noted that contribute
to the certainty of the diagnosis. Each child
may experience symptoms differently. Symptoms
may include:
- heart and blood vessels
- dilation of the
aorta
- leakage of the
aortic valve (aortic regurgitation)
- tears in the aorta
(aortic dissection)
- skeletal
- deformities of
the breastbone
- scoliosis - a lateral,
or sideways curvature and rotation of the
back bones (vertebrae), giving the appearance
that the person is leaning to one side.
- misalignment of
certain bones
- joint contractures
- unusual arm span
- long fingers and
toes
- eye
- dislocation of
the lens (the transparent structure inside
the eye that focuses light rays onto the
retina)
The
symptoms of Marfan syndrome may resemble other
problems or medical conditions. Always consult
your child's physician for a diagnosis.
In addition
to a complete medical history and physical examination,
your child's physician may complete a family medical
history to look for other family members with
known Marfan syndrome or some of the characteristics
of the disease.
Other
diagnostic tests for Marfan syndrome may include
the following:
- electrocardiogram
(ECG or EKG) - a test that records
the electrical activity of the heart, shows
abnormal rhythms (arrhythmias or dysrhythmias),
and detects heart muscle damage.
- echocardiography (echo)
- a procedure that evaluates the
structure and function of the heart by using
sound waves recorded on an electronic sensor
that produce a moving picture of the heart and
heart valves.
- complete eye examination
- an examination of the interior
of the eye, performed by an ophthalmologist,
using a device called a slit lamp.
- x-ray -
a diagnostic test which uses invisible electromagnetic
energy beams to produce images of internal tissues,
bones, and organs onto film.
- DNA studies -
a blood sample sent to the genetics lab can
analyze the FBN1 gene to determine whether a
mutation is present; not all mutations in the
fibrillin gene cause Marfan syndrome. Similarly,
not all persons with Marfan syndrome have a
mutation in this gene. Sometimes, a type of
DNA study called a linkage study, which examines
the DNA of several family members, can aid in
tracking the gene in the family. However, because
of these limitations, the diagnosis of Marfan
syndrome is primarily based on clinical findings.
In order
to be diagnosed with Marfan syndrome, your child
must exhibit several characteristics from a detailed
list. Your child needs to have a significant number
of the symptoms on the checklist in order to be
diagnosed with the disorder. Your child's physician
will make the diagnosis based on medical and family
history and other factors, as well as symptoms
your child may exhibit.
Marfan
syndrome may be easier to diagnose as children
age, as many of the features of the disorder become
more obvious as your child grows.
Specific
treatment for Marfan syndrome will be determined
by your child's physician based on:
- your child's age, overall
health, and medical history
- extent of the disorder
- your child's tolerance
for specific medications, procedures, or therapies
- expectations for the
course of the disease
- your opinion or preference
At the
present time, there is no cure for the disorder.
Treatment is based on determining which organ
systems are affected and managing the problems
that arise. Recommendations for managing Marfan
syndrome may include the following:
- an annual echocardiogram,
or echo (to monitor the heart and aorta)
- periodic eye examination
by an ophthalmologist
- monitoring of the skeletal
system for abnormalities (such as scoliosis)
that can be noted in childhood or adolescence
- lifestyle adjustments
(to reduce the risk of injury to the aorta,
such as avoiding contact sports or stressful
exercise)
- the use of antibiotics
before dental procedures (to reduce the chance
of developing a heart infection)
Genetic
counseling is important for people who have Marfan
syndrome and are planning to have a family. If
one parent has the disorder, there is a 50 percent
chance, with each pregnancy, for a child to also
have Marfan syndrome. In addition, women with
Marfan syndrome who become pregnant have significant
risks for their health during pregnancy, due to
the added stress that a pregnancy puts on the
heart. Avoidance of pregnancy is often recommended
to reduce the risk of injury to the aorta.
Heart
and blood vessel problems pose the largest threat
to a person with Marfan syndrome, which emphasizes
the importance of regular evaluation by your child's
physician. Consult your child's physician for
more information regarding the specific outlook
for your child.
With
advances in the diagnosis, evaluation, and management
of the organ abnormalities associated with Marfan
syndrome, the life expectancy for a person with
the disease has nearly doubled in the past 25
years. Today, individuals with Marfan syndrome
can expect to live about 70 years.
For
women with Marfan syndrome, pregnancy and childbirth
pose significant risks. These women should be
evaluated with echocardiography prior to becoming
pregnant. Other diagnostic imaging procedures,
such as computed tomography angiography (CTA)
or magnetic resonance angiography (MRA), may be
used to assess risks. Cesarean delivery (C-section)
is generally recommended for pregnant women with
Marfan syndrome to prevent strain on the aorta
and decrease the risk of aortic dissection during
labor.
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