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$Unique_ID{BRK04044}
$Pretitle{}
$Title{Neuropathy, Congenital Hypomyelination}
$Subject{Neuropathy Congenital Hypomyelination CHN Congenital Dysmyelinating
Neuropathy Congenital Hypomyelinating Polyneuropathy CHN Congenital
Hypomyelination Congenital Hypomyelination Neuropathy Congenital
Hypomyelination Onion Bulb Polyneuropathy Congenital Neuropathy
Hypomyelination Congenital Neuropathy Early Infantile Neuropathy Infantile
Neuropathy Hypomyelination Neuropathy Dejerine-Sottas Disease Guillain-Barre
Syndrome }
$Volume{}
$Log{}
Copyright (C) 1990 National Organization for Rare Disorders, Inc.
822:
Neuropathy, Congenital Hypomyelination
** IMPORTANT **
It is possible that the main title of the article (Congenital
Hypomyelination Neuropathy) is not the name you expected. Please check the
SYNONYM listing to find the alternate names and disorder subdivisions covered
by this article.
Synonyms
CHN
Congenital Dysmyelinating Neuropathy
Congenital Hypomyelinating Polyneuropathy (CHN)
Congenital Hypomyelination
Congenital Hypomyelination Neuropathy
Congenital Hypomyelination (Onion Bulb) Polyneuropathy
Congenital Neuropathy caused by Hypomyelination
Congenital Neuropathy
Early Infantile Neuropathy
Infantile Neuropathy
Hypomyelination Neuropathy
Information on the following disorders can be found in the Related
Disorders section of this report:
Dejerine-Sottas Disease
Guillain-Barre Syndrome
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 of this report.
Congenital Hypomyelination Neuropathy is a neurological disorder present
at birth. Major symptoms can include respiratory difficulty, muscle weakness
and incoordination, poor muscle tone, absence of reflexes, difficulty in
walking, and/or impaired abilities to feel or move part of the body.
Symptoms
Symptoms of Congenital Hypomyelination Neuropathy and the severity of these
symptoms vary from patient to patient. Major symptoms can include delayed
motor (muscle) development (ability to turn over, stand, crawl, walk, etc.),
muscle weakness, poor muscle tone (hypotonia), impaired muscle coordination,
absence of reflexes (areflexia), difficulty in walking or crawling, and/or
impaired ability to feel or move part of the body (mild distal palsy). In
some infants, respiratory problems or difficulty in swallowing may occur.
Abnormal microscopic changes in certain nerves such as sural nerves (located
in the calf of the leg) can occur.
Causes
The exact cause of Congenital Hypomyelination Neuropathy is unknown. The
cause of many disorders involving the myelin sheath (the protective sheath
surrounding the nerves), such as Multiple Sclerosis, is unknown. A recurrent
loss and repair of myelin causes Congenital Hypomyelination Neuropathy.
Scientists do not yet know why the myelin disappears, nor do they know why it
grows back.
Some researchers believe, although this has not yet been established,
that Congenital Hypomyelination Neuropathy may be a subtype of Dejerine-
Sottas Disease which is inherited as an autosomal dominant trait. Human
traits, including the classic genetic diseases, are the product of the
interaction of two genes, one received from the father and one from the
mother. In autosomal dominant disorders, a single abnormal gene, contributed
by either parent, overrides the normal gene contributed by the other parent
causing disease. Individuals with one affected parent have a 50% chance of
inheriting the disorder. (For more information on Dejerine-Sottas Disease,
see the Related Disorders section of this report).
Other disorders characterized by the loss and repair of the myelin sheath
may be autoimmune disorders. In autoimmune disorders the body's defenses
against disease (e.g. antibodies or lymphocytes) attack healthy tissue for
unknown reasons.
Affected Population
Congenital Hypomyelination Neuropathy is a rare disorder present at birth.
It affects males and females in equal numbers.
Related Disorders
Dejerine-Sottas Disease is a hereditary neurological disorder which
progressively affects muscle function. Peripheral nerves become enlarged and
thickened causing an irregular progression of muscle weakness. Pain,
weakness, numbness, and a tingling, prickling or burning sensation can occur
in the patient's legs. Other symptoms include loss of heat sensitivity,
absence of reflexes and atrophy of leg muscles. The hand and forearm muscles
may become weak in later stages. Mild vision difficulties may also occur.
(For more information on this disorder, choose "Dejerine-Sottas" as your
search term in the Rare Disease Database).
Guillain-Barre Syndrome (Acute Idiopathic Polyneuritis) occurs when the
body's immune system (antibodies, lymphocytes) attacks the nerves, damaging
the nerve's myelin and axon. Nerve signals are delayed and altered, causing
weakness and paralysis of the muscles of the legs, arms, and other parts of
the body along with abnormal sensations. When muscle nerves are damaged, the
patient experiences aching and weak muscles, difficulty getting up from
chairs or walking stairs, difficulty lifting objects, shortness of breath,
and/or difficulty in swallowing. With proper treatment, most patients with
Guillain-Barre Syndrome can expect to lead full and active lives. (For more
information on this disorder, choose "Guillain" as your search term in the
Rare Disease Database).
Therapies: Standard
Testing for Congenital Hypomyelination Neuropathy may include recording of
electrical impulses produced by the muscles (electromyogram), as well as
nerve and/or muscle biopsies. Treatment of Congenital Hypomyelination
Neuropathy is symptomatic and supportive.
Therapies: Investigational
This disease entry is based upon medical information available through
December 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 Congenital Hypomyelination Neuropathy, please
contact:
National Organization for Rare Disorders
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 genetic information 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, Volume 1, 15th Ed.: Robert Berkow, M.D., ed.-in-chief;
Merck, Sharp, and Dohme Laboratories, 1987. Pp. 1433-1434.
A CASE OF CONGENITAL HYPOMYELINATION NEUROPATHY. CLINICAL,
MORPHOLOGICAL, AND CHEMICAL STUDIES. W.R. Kennedy, et al.; Arch Neurol (Jun
1977; issue 34 (6)). Pp. 337-345.
CONGENITAL HYPOMYELINATION NEUROPATHY IN A NEWBORN. S. Hakamada, et al.;
Neuropediatrics (Aug 1983; issue 14 (3)). Pp. 182-183.
CONGENITAL HYPOMYELINATION POLYNEUROPATHY. PATHOLOGICAL FINDINGS
COMPARED WITH POLYNEUROPATHIES STARTING LATER IN LIFE. F. Guzzetta, et al.;
Brain (Jun 1982; issue 105 (Pt 2)). Pp. 395-416.
TWO CASES OF CONGENITAL HYPOMYELINATION NEUROPATHY. N. Tachi, et al.;
Brain Dev (1984; issue 6 (6)). Pp. 560-565.