Fukuyama Type Congenital Muscular Dystrophy
NORD is very grateful to Chang-Yong Tsao, MD, FAAN, FAAP, Professor of Clinical Pediatrics and Neurology, College of Medicine and Public Health, Ohio State University, for assistance in the preparation of this report.
Synonyms of Fukuyama Type Congenital Muscular Dystrophy
- cerebromuscular dystrophy, Fukuyama type
- congenital muscular dystrophy, Fukuyama type
- micropolygyria with muscular dystrophy
- muscular dystrophy, congenital, Fukuyama type
- muscular dystrophy, congenital progressive with mental retardation
- muscular dystrophy, congenital with central nervous system involvement
- muscular dystrophy, fukuyama type
- No subdivisions found.
Fukuyama type congenital muscular dystrophy (FCMD) is one of several forms of a rare type of muscular dystrophy known as congenital muscular dystrophy. It is inherited as an autosomal recessive trait. Symptoms of this disorder are apparent at birth and progress slowly. In addition to general muscle weakness and deformities of the joints (contractures), FCMD is often accompanied by seizures, mental retardation and speech problems. This disorder is predominantly found in Japan.
Infants with Fukuyama congenital muscular dystrophy are "floppy" at birth and usually have problems sucking and swallowing. They have a weak cry and there is a loss of muscle tone as well as weakness of the muscles. The joints in the knees and elbows may be in a fixed position (contractures) and reflexes of the tendons are poor.
Mental retardation is characteristic of this form of muscular dystrophy. Also, some affected infants and children have seizures. A sunken chest, and a severe form of grand mal seizures called status epilepticus has been found in a few individuals with FCMD.
Fukuyama congenital muscular dystrophy is inherited as an autosomal recessive trait. It occurs as a result of a gene mutation on the long arm of chromosome 9 (9q31). This gene gives instructions for the production of (codes for) a protein known as fukutin. The normal role of this protein isn't yet well understood.
Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For example, "chromosome 9q31" refers to band 31 on the long arm (q) arm of chromosome 9. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.
All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
Fukuyama type congenital muscular dystrophy is almost nonexistent in the United States, but in Japan is second only to Duchenne muscular dystrophy in frequency. The incidence in Japan is reported as about 0.7-1.2 cases per 100,000 children.
Symptoms of the following disorders can be similar to those of Fukuyama type congenital muscular dystrophy. Comparisons may be useful for a differential diagnosis:
Becker muscular dystrophy (BMD) is much like Duchenne muscular dystrophy and is characterized by weakness of the muscles of the legs that usually first is noticed in a boy's pre-teen and teen years. The muscle weakness is progressive but milder in severity than in Duchenne muscular dystrophy. (For more information on this disorder, choose "Muscular Dystrophy, Becker" as your search term in the Rare Disease Database.)
Distal muscular dystrophy (DD) generates weakness in the legs but, in addition, affects the strength of the muscles of the hands and feet. This form of MD progresses more slowly than others and generally affects patients less severely.
Duchenne muscular dystrophy (DMD) is the most rapidly progressive form of muscular dystrophy and one of the most common. This muscle-wasting disorder, which affects boys almost exclusively, typically has its onset between the ages of two and five, and progresses rapidly. For a brief period, between ages three and seven, the child's natural growth and development may produce a deceptive improvement in this condition. However, muscle degeneration continues, resulting in weakness that advances rapidly after the age of eight or nine. (For more information on this disorder, choose "Muscular Dystrophy, Duchenne " as your search term in the Rare Disease Database.)
Emery-Dreifuss muscular dystrophy (EDMD) usually presents during childhood or the teen years. It affects the muscles of the calves, shoulders and upper arms. EDMD progresses slowly. Contractions of the calf muscles are prominent. Among other significant symptoms are the abnormal heartbeats and EKGs caused by peculiarities in the way electrical impulses pass through the heart. (For more information on this disorder, choose "Muscular Dystrophy, Emery-Dreifuss" as your search term in the Rare Disease Database.)
Fascioscapulohumeral muscular dystrophy (FSH) affects both males and females, and strikes during the teen years or the decade afterward. It usually generates weakness in the muscles of the face, shoulders, and upper arms. Less frequently, it may also affect the muscles of the legs and hips. (For more information on this disorder, choose "Fascioscapulohumeral Muscular Dystrophy" as your search term in the Rare Disease Database.)
Limb-girdle muscular dystrophy (LGMD) usually begins in the teens years or early adulthood. The first muscles affected are usually those of the shoulders and hips. Slowly, the disorder progresses to include the arms and legs. (For more information on this disorder, choose "Muscular Dystrophy, Limb-Girdle" as your search term in the Rare Disease Database.)
Myotonic dystrophy, also known as Steinert's disease, presents as muscle weakness. It may specifically involve facial muscle weakness, slack jaw, and drooping eyelids. The disorder is progressive, usually leading to severe disability over a period of years. (For more information on this disorder, choose "Dystrophy, Myotonic" as your search term in the Rare Disease Database.)
Oculopharyngeal muscular dystrophy (OPMD) is a disorder of adulthood that affects both males and females. Initially, it weakens the muscles of the eyes and throat causing symptoms such as drooping eyelids (ptosis) and difficulty in swallowing or eating (dysphagia). The disorder may progress to affect the muscles of the face and neck as well as, in even rarer cases, the muscles of the thighs.
The diagnosis depends on a thorough physical examination and medical history. In addition, the physician will look for information to assist in the diagnosis from several tests such as blood tests to detect abnormally high levels of a particular enzyme (creatine kinase) released form the cells of damaged muscles, electromyographic studies to determine the area of muscle that is damaged, and muscle biopsy to distinguish muscular dystrophy from other neuromuscular disorders.
Patients with Fukuyama congenital muscular dystrophy may benefit from physical therapy to help prevent joints from becoming fixed.
For patients who have seizures, anti-convulsant drugs such as phenytoin, valproic acid, phenobarbitol, clonazepam, ethusuximide, primidone, corticotropin, and corticosteroid drugs may help prevent and control seizures.
Genetic counseling will be of benefit for patients and their families.
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Contact for additional information about Fukuyama type congenital muscular dystrophy:
Chang-Yong Tsao, MD, FAAN, FAAP
Professor of Clinical Pediatrics and Neurology
College of Medicine and Public Health
Ohio State University
Columbus, Ohio 43210
Fukuyama Type Congenital Muscular Dystrophy Resources
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