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Untitled Document
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| Heart
Disease |
| Some Heritable Diseases Cause Cardiomyopathy |
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By Stephanie
Trelogan, MS
Reviewed
by Andy Avins, MD
and Christopher
Friedrich, MD, PhD
Many cases of hereditary cardiomyopathy
are caused by mutations
in specific genes. However,
cardiomyopathy can aslo occur as a result of other known
hereditary syndromes. These
syndromes include hemochromatosis
and diabetes, as well as other genetic
diseases. Clues from your family medical history
can help determine whether any of these other hereditary
diseases are the cause of cardiomyopathy in your family.
Three of the most common types of diseases that can
result in cardiomyopathy are amyloid disease, lysosomal
storage diseases, and neuromuscular disorders.
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Amyloid
Disease
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Amyloids
are fibrous proteins that can
accumulate outside of cells all
over the body. When they build up in and around the heart
muscle, amyloid deposits can cause cardiomyopathy, arrhythmias,
and congestive heart failure. Inherited
forms of cardiomyopathy due to amyloid plaques –
called familial amyloid cardiomyopathies – are inherited
in an autosomal dominant fashion,
which means that you only need to inherit a mutated copy
of the gene from one parent in order to be at risk. Most
cases of this disease are due to mutations in the gene
for trasthyretin, which transports certain chemicals in
the blood. One mutation in this gene is present in nearly
four percent of people of African descent. However, there
are over 50 different mutations that have been identified
in the trasthyretin gene, as well as mutations in other
genes that cause familial amyloid cardiomyopathies.
Researchers
don't know how common familial amyloid cardiomyopathies
are because the disease is often not diagnosed. Also,
because the disease has a late onset, people who carry
the mutation may develop heart disease for different
reasons, or die of different illnesses before the cardiomyopathy
develops.
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Lysosomal
Storage Disease
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Lysosomes
are sacs of enzymes within
the cell that play an important role in breaking down
various molecules. When these enzymes fail, the molecules
accumulate to toxic levels. Each enzyme within the lysosome
is encoded by a different gene, and causes a different
autosomal recessive disease when
mutated.
Most
lysosomal storage diseases cause problems throughout
the body. These rare diseases are usually diagnosed
early because a problem is very obvious, such as mental
retardation, an enlarged head, skeletal deformities,
or skin problems. Several lysosomal storage diseases
also have cardiomyopathy as one of their features.
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Neuromuscular
Disorders
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Neuromuscular
disorders — or muscular dystrophies — affect
the function of all muscles, including the heart muscle.
As with lysosomal storage diseases, there are many different
genes that can be mutated to cause muscular dystrophies.
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References
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Giles,
T. D. (1997) Dilated Cardiomyopathy. In P. A. Poole-Wilson,
et al. (Eds.), Heart Failure. (pp. 401–422). New
York, NY: Churchill Livingstone, Inc.
Jamieson,
C. R., et al. (1994) Mapping a gene for Noonan syndrome
to the long arm of chromosome 12. Nature Genetics,
8, 357-360.
Vosberg,
H.-P. & McKenna, W. J. (1997) Cardiomyopathies.
In D. L. Rimoin, et al. (Eds.), Emery and Rimoin's Principles
and Practice of Medical Genetics, volume 1 (pp. 843-877).
New York, NY: Churchill Livingstone, Inc.
Benson,
MD (1997). Aging, Amyloid, and Cardiomyopathy. New
Eng. J. Med. 336:
Jacobson
DR, et al. (1996) Revised transthyretin Ile 122 allele
frequency in African-Americans. Hum Genet 98:236-8.
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