Myopathy, Scapuloperoneal

Disease Overview

Scapuloperoneal myopathy is a rare genetic disorder characterized by weakness and wasting of certain muscles. Symptoms are usually limited to the shoulder blade area (scapula) and the smaller of the two leg muscle groups below the knee (peroneal). Facial muscles may be affected in a few cases. The leg symptoms often appear before the shoulder muscles become weakened. The rate of progression of the disorder varies from case to case. This condition can also occur in combination with other disorders. Scapuloperoneal myopathy is inherited as an autosomal dominant trait.

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Synonyms

Scapuloperoneal Muscular Dystrophy
Scapuloperoneal Syndrome, Myopathic Type

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Signs & Symptoms

Symptoms of scapuloperoneal myopathy primarily include muscle weakness and wasting usually limited to muscles in the shoulder blade and girdle area and the legs below the knees. This disorder can begin in childhood or adulthood. The progression rate and severity may vary greatly, with some cases progressing more quickly than others. In most cases, the progression is slow.

The shoulder muscles are affected first, in most cases. In some cases, shoulder involvement may precede lower leg involvement by years or decades. In some cases, lower leg involvement may precede shoulder involvement. In rare cases, some facial muscles may be mildly affected.

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Causes

Scapuloperoneal myopathy is inherited as an autosomal dominant trait. 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 other normal gene and resulting in the appearance of the disease. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.

In some cases, scapuloperoneal myopathy may be due to new genetic changes (mutations) that appear to occur spontaneously for unknown reasons (sporadically).

Investigators have determined that some cases of scapuloperoneal myopathy may be caused by disruption or changes (mutations) of a gene located on the long arm (q) of chromosome 12 (12q13.3-q15). Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as “p” and a long arm identified by the letter “q.” Chromosomes are further subdivided into bands that are numbered. For example, “chromosome 12q13.3-q15” refers to bands 13.3-15 on the long arm of chromosome 12.

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Affected populations

Scapuloperoneal myopathy affects males and females in equal numbers. Symptoms may begin in childhood or during adulthood. Scapuloperoneal myopathy is a rare disorder; the exact prevalence of this disorder in the general population is unknown.

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Disorders with Similar Symptoms

Symptoms of the following disorders can be similar to those of scapuloperoneal myopathy. Comparisons may be useful for a differential diagnosis:

Scapuloperoneal amyotrophy (also known as Kaeser syndrome or scapuloperoneal syndrome, neurogenic type) is characterized by muscle weakness and wasting (atrophy) below the knees accompanied by foot abnormalities and an unusual walk. Eventually, the shoulder muscles may also become involved. Nerve impulses may become measurably slowed, which does not occur in scapuloperoneal myopathy. Pain, unusual sensations in the legs, heart problems, and muscle contractures may also occur. Scapuloperoneal amyotrophy is inherited as an autosomal dominant trait.

Facioscapulohumeral dystrophy (FSHD) is a rare disorder that belongs to a group of disorders known as the muscular dystrophies. FSHD is characterized by weakness of facial muscles as well as weakness and wasting (atrophy) of muscles of the shoulders and arms. The disorder usually progresses slowly over many years and decades, although there may be periods of rapid deterioration. Associated abnormalities may include an impaired ability to completely close the eyes, limited movements of the lips, and difficulties raising the arms over the head. Affected individuals may also eventually develop weakness and associated wasting (atrophy) of muscles of the hips and thighs and/or involvement of lower leg muscles, potentially leading to an impaired ability to flex the foot upward (footdrop). In those with FSHD, the disease course may be variable, with relatively slow, moderate, or rapid progression or, in other instances, nonprogressive involvement of certain muscles. However, FSHD is most typically characterized by relatively slow disease progression. In some cases, the disorder is inherited as an autosomal dominant trait. (For more information on this disorder, choose Facioscapulohumeral Muscular Dystrophy as your search term in the Rare Disease Database.)

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Standard Therapies

There is no specific treatment for individuals with scapuloperoneal myopathy. Treatment may include specified amounts of therapeutic exercise and physical therapy alternating with periods of rest.

Genetic counseling may benefit affected individuals and their families. Other treatment is symptomatic and supportive.

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Clinical Trials and Studies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

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References

JOURNAL ARTICLES

Pal E, et al. Familial scapuloperoneal myopathy and mitochondrial DNA defect. Eur Neurol. 1999;42:211-16.

Milanov I, et al. Differential diagnosis of scapuloperoneal syndrome. Electromyogr Clin Neurophysiol. 1997;37:73-78.

Wilhelmsen KC, et al. Chromosome 12-linked autosomal dominant scapuloperoneal muscular dystrophy. Ann Neurol. 1996;39:507-20.

Isozumi K, et al. Linkage of scapuloperoneal spinal muscular atrophy to chromosome 12q24.1-q24.31. Hum Mol Genet. 1996;5:1377-82.

Emery AE, et al. Emery-Dreifuss muscular dystrophy and other related disorders. Br. Med Bull. 1989;45:772-87.

Yee WC, et al. Adult onset scapuloperoneal myopathy: diagnostic value of nerve morphometry and multiple muscle biopsies. J Neurol Neurosurg Psychiatry. 1988;51:808-13.

Wagner MB, et al. Serial isokinetic evaluations used for a patient with scapuloperoneal muscular dystrophy. Phys Ther. 1986;66:1110-13.

Todman DH, et al. Scapuloperoneal myopathy. Clin Exp Neurol. 1984;20:169-74.

Spalke G, et al. The differential diagnosis of scapuloperoneal amyotrophy. J Neurol. 1976;15:253-69.

Thomas PK, et al Adult onset scapuloperoneal myopathy. J Neurol Neurosurg Psychiatry. 1975;38:1008-15.

FROM THE INTERNET

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:181430; Last Update:10/23/96.

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:181400; Last Update:3/13/98.

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Rare Disease Database