AMD - Acid Maltase Deficiency -
Pompe's Disease
A Brief
Summary
The Acid
Maltase Deficiency Association was established in
1995 to assist in funding research and to promote public
awareness of Pompe disease. Pompe disease is one
of a family of 49 rare genetic disorders known as Lysosomal
Storage Diseases or LSDs. Pompe disease is also known
as Acid Maltase Deficiency or Glycogen Storage Disease
type II. It affects an estimated 5,000 to 10,000
people in the developed world.
Cause of
Pompe disease.....
Pompe disease is caused by a complete or partial
deficiency of the lysosomal enzyme, alpha-glucosidase.
This enzyme is necessary to break down glycogen and to
convert it into glucose. Without this enzyme, glycogen, a
thick sticky substance, accumulates in the lysosomes
(sacs within the muscle cells) and leads to severe muscle
degradation. It predominately affects the heart,
skeletal, and respiratory muscles of the patient.
Progression
of Pompe disease.....
Patients with the infantile form of the
disease are the most severely affected. These babies
appear normal at birth, but exhibit symptoms by 2-3
months of age (or earlier). Progression is rapid. These
patients are so severely affected that they become
"limp" unable to feed or move. Their hearts
become massively enlarged, and they typically die of
cardio-respiratory failure before reaching 12 months of
age.
In the delayed
onset form progression of the disease is less rapid.
Symptoms can manifest at any age of life and can greatly
affect the quality of life as well as the life span of
the afflicted person. Delayed onset patients that develop
symptoms in childhood are more severely affected and
typically die by the second or third decade of life. As
the disease progresses, patients lose mobility, become
wheelchair bound or bedridden. Respiratory functions
greatly diminish and mechanical ventilation becomes
necessary. Death results from cardio-respiratory
complications.
Clinical
forms of Pompe disease.....
Clinical forms of the disease vary according to the age
of onset and percent of enzyme activity.
The
Infantile Form.....
appears in the first few months after birth and is
characterized by a rapid build-up of glycogen in muscle
tissue causing severe muscle weakness and enlargement of
the heart and liver. Respiratory and heart complications
lead to death by the age of 12 months. The infantile form
is characterized by a total lack of the alpha-glucosidase
enzyme or by total inactivity of the enzyme.
The
Delayed Onset Form.....
can present at any age. Delayed onset patients produce a
minimal amount of enzyme. Progression and severity of the
disease is probably attributable to the amount of enzyme
produced and to the age of onset of symptoms. Glycogen
build up is not as rapid as in the infantile form but the
disease is progressive and can greatly decrease the life
span of the afflicted person. In the delayed onset form
deterioration of muscle is mainly confined to the
skeletal muscles, the diaphragm, the limb-girdle, and the
trunk. Respiratory complications are the main cause of
death. Delayed onset patients that present symptoms early
in life are usually more severely affected and rarely
survive past the second or third decade of life. Patients
that experience onset later in life generally progress at
a slower pace.
Enzyme
Replacement Therapy.....
In 1999 the first human clinical trials for Pompe
disease with enzyme replacement therapy began in the
Netherlands with four infantile patients at Sophia
Children’s Hospital in Rotterdam. Six months later
another clinical trial was started in the Netherlands
with three delayed onset patients. At the same time Duke
University Medical Center in the US initiated a new
infantile clinical trial with three patients.
Today there
are five sites conducting clinical trials with enzyme
replacement therapy. Although the number of patients in
these trials is small the results have been promising.
Genzyme
Corporation, the sponsor of the clinical trials, plans to
start expanded clinical trials at additional sites in
2003. They are currently working with regulatory
authorities in the US and in Europe to obtain approval
for ERT for Pompe disease and hope to have an approved
product available for world-wide marketing in 2005.
Gene
Replacement Therapy.....
Gene replacement therapy will eventually be the cure
for Pompe disease and other rare disorders. But until
this dream is realized, enzyme replacement therapy offers
hope in the near future for those affected by the
devastation of Pompe disease.
Why the
AMDA was formed.......
The founders of the organization became dedicated to
finding answers to their questions after their daughter
was diagnosed with Pompe disease at the age of
twelve. Although she had many medical problems starting
in early childhood, it was very difficult to find a
proper diagnosis for her symptoms.
This is often
the case with delayed onset patients whose symptoms and
progression vary. They were eventually led in the right
path by a relative, a pediatrician at the Mayo Clinic in
Rochester, Minnesota. Following extensive testing and a
muscle biopsy, she was diagnosed with Pompe disease.
The prognosis
was dire. The parents were told that the disease was
progressive, that there was no treatment or cure, and
that their daughter would only live to the second decade.
At that time
there was minimal information available about Pompe
disease, and the parents were uncertain about how much
time Tiffany had. After months of investigation, however,
they found that several major medical centers in the
United States and in Europe were working on enzyme and
gene replacement therapy for Pompe disease.
Today, there
is hope for Tiffany’s future. She is participating
in a clinical trial for enzyme replacement therapy. At
this time, she is the only delayed onset Pompe patient in
the US currently receiving enzyme replacement therapy.
We
Need Your Help!
To further research and find a cure for AMD, private
funds must be raised. If you are interested in learning
more about AMD and would like to make a contribution in
support of necessary research, please contact us at:
 To contact the AMDA
or
AMDA
Acid Maltase Deficiency Association
P.O. Box 700248
San Antonio, Texas 78270-0248
Phone: 210-494-6144
Fax: 210-490-7161
Email: tianrama@aol.com
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