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$Title{Nemaline Myopathy}
$Subject{Nemaline Myopathy Rod Myopathy Congenital Rod Disease }
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Copyright (C) 1986, 1987, 1989, 1990 National Organization for Rare
Disorders, Inc.

151:
Nemaline Myopathy

** IMPORTANT **
It is possible that the main title of the article (Nemaline Myopathy) is
not the name you expected.  Please check the SYNONYM listing to find
alternate names and disorder subdivisions covered by this article.

Synonyms

     Rod Myopathy
     Congenital Rod Disease

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section.


Nemaline myopathy is a hereditary muscular disease characterized by
weakness and "floppiness" of skeletal muscles.  The disease derives its name
from the presence of very fine threads or rods called "nemaline rods" in the
microscopic muscle fibers.

Symptoms

Nemaline myopathy is evident from birth.  Thighs and upper arms are thin and
extremely weak.  The muscles of the trunk (i.e., the chest, back, and
abdomen) are also weak so that posture may be abnormal.  Deep tendon reflexes
(such as knee or ankle jerks) may be absent.  Muscle tone is very poor, and
the muscles are soft and the child seems "floppy".

If the muscles involved in swallowing or breathing become severely
involved, the disease may be life threatening.  Otherwise, the prognosis is
indeterminate.  The muscular dysfunction progresses during childhood, but
overall growth of muscle mass may counterbalance this, so that the condition
may improve overall as the child grows.

Causes

Nemaline Rod Disease is inherited, either through a dominant or recessive
mode of transmission.

Human traits including the classic genetic diseases, are the product of
the interaction of two genes for that condition, one received from the father
and one from the mother.

In dominant disorders, a single copy of the disease gene (received from
either the mother or father) will be expressed "dominating" the normal gene
and resulting in appearance of the disease.  The risk of transmitting the
disorder from affected parent to offspring is 50% for each pregnancy
regardless of the sex of the resulting child.

In recessive disorders, the condition does not appear unless a person
inherits the same defective gene from each parent.  If one receives one
normal gene and one gene for the disease, the person will be a carrier for
the disease, but usually will show no symptoms.  The risk of transmitting the
disease to the children of a couple, both of whom are carriers for a
recessive disorder, is twenty-five percent.  Fifty percent of their children
will be carriers, but healthy as described above.  Twenty-five percent of
their children will receive both normal genes, one from each parent and will
be genetically normal.

The biochemical defect involved is not known, although the nemaline rods
suggest an abnormal accumulation of some protein.

Related Disorders

Nemaline myopathy may occur in the same families as Central core Disease, a
milder, less progressive, but similar muscle disease.

Therapies:  Standard

Treatment of Nemaline Myopathy is symptomatic and supportive.  Symptoms of
the disease often improve as the child gets older.

Therapies:  Investigational

This disease entry is based upon medical information available through
January 1990.  Since NORD's resources are limited, it is not possible to keep
every entry in the Rare Disease Database completely current and accurate.
Please check with the agencies listed in the Resources section for the most
current information about this disorder.

Resources

For more information on Nemaline Myopathy, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     (203) 746-6518

     NIH/National Institute of Neurological Disorders & Stroke (NINDS)
     9000 Rockville Pike
     Bethesda, MD  20892
     (301) 496-5751
     (800) 352-9424

For information on genetics and genetic counseling referrals, please
contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     (914) 428-7100

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     (301) 652-5553

References

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  P. 1452.

THE METABOLIC BASIS OF INHERITED DISEASE, 6th ed.:  Charles R. Scriver,
et al.; eds., McGraw Hill, 1989.  P. 2892.