Limb-Girdle Muscular Dystrophy Health Article

Signs and symptoms

Each type of LGMD has a different range of symptoms. The symptoms can even vary between individuals with the same type of LGMD. The age of onset of symptoms can occur from infancy to adulthood. The most common symptom of LGMD is muscle weakness and deterioration and involves the muscles around the hips and shoulders. The disorder progresses at a different rate in each person. Although individuals with an onset of the disorder in adulthood may have a slower progression and milder symptoms, the exact progression and extent of muscle deterioration cannot be predicted,.

The first noticeable symptom of LGMD is often a waddling gait due to weakness of the hip and leg muscles. Difficulties in rising from a chair or toilet seat and difficulties in climbing stairs are common. Eventually, walking may become impossible and lead to resorting to a wheelchair or scooter for locomotion. Enlargement or a decrease in size of the calf muscles can also be seen. Some individuals with LGMD also experience contractures and muscle cramps. The limited mobility associated with LGMD can result in muscle soreness and joint pain.

Lifting heavy objects, holding the arms outstretched, and reaching over the head can become impossible for people affected with LGMD because of weaknesses in the shoulder muscles. Some individuals with LGMD may eventually have difficulties swallowing and feeding themselves. Sometimes the back muscles can become weakened and result in scoliosis (curvature of the spine).

LGMD can occasionally result in a weakening of the heart muscles and/or the respiratory muscles. Some people may experience a weakening of the heart muscles (cardiomyopathy). Others may develop a conduction defect, an abnormality in the electrical system of the heart that regulates the heartbeat. A weakening of the muscles necessary for respiration can cause breathing difficulties. LGMD does not affect the brain and the ability to reason and think. Individuals with LGMD also do maintain normal bladder and bowel control and sexual functioning.

Diagnosis

No single test can diagnose LGMD. A diagnosis is based on clinical symptoms, physical examinations, and a variety of tests. The physician will first take a medical history to establish the type of symptoms experienced and the pattern of muscle weakness. Questions will usually be asked about the family history to see whether other relatives have similar symptoms.

It is necessary for the doctor to establish whether the weakness is due to problems with the muscles or due to a problem with the nerves that control the muscles. Sometimes this can be accomplished through a physical examination. Electromyography testing is often performed to establish whether the weakness is in the nerves or the muscles. During electromyography, a needle electrode is inserted into the muscle and measurements are taken of the electrical activity of the muscle in response to stimulation by the nerves.

A blood test that measures the amount of creatine kinase is often performed. Creatine kinase is an enzyme that is produced by damaged muscles. High levels of creatine kinase suggest that the muscle is being destroyed, but the high levels cannot indicate the cause of the damage. The most common causes of increased creatine kinase levels are muscular dystrophy and muscle inflammation.

A muscle biopsy will often be performed if LGMD is suspected. During the muscle biopsy, a small amount of muscle is surgically removed. The muscle sample is examined to check for changes that are characteristic of muscular dystrophies. The amount and type of muscle proteins present in the sample can sometimes help to confirm a diagnosis of LGMD and can sometimes indicate the type of LGMD.

Ultimately, a diagnosis can be difficult to make as there are many types of LGMD and a wide range of symptoms. It can also be difficult to differentiate LGMD from other muscular dystrophies that have similar symptoms, such as Becker and Duchenne muscular dystrophies. Anyone suspected of having LGMD should, therefore, consider undergoing testing for other types of muscular dystrophies.

DNA testing for some forms of LGMD is now available through clinical and commercial laboratories. DNA testing is complicated by the many genes and the types of gene mutations (changes) that can cause LGMD. Some research laboratories are looking for the gene mutations that cause LGMD and may detect the gene mutation or mutations responsible for LGMD in a particular individual. DNA testing may be performed on a sample of blood cells or a sample of muscle cells. If an autosomal dominant gene mutation is detected in someone with LGMD, then both of the individual's parents can be tested to see if the gene mutation was inherited. If the gene mutation was inherited, siblings can be tested to see if they have inherited the mutated gene. If autosomal recessive gene mutations are detected, relatives, such as siblings, can be tested to see if they are carriers.

Prenatal testing for LGMD is only available if DNA testing has detected an autosomal dominant LGMD gene mutation in one parent or an autosomal recessive gene mutation in both parents. Cells for prenatal testing are obtained through an amniocentesis or chorionic villus sampling (CVS). These cells are analyzed for the LGMD gene mutation or mutations that were found in one or both parents.