| Muscular dystrophy (MD) refers to a group of genetic, hereditary muscle diseases that cause progressive muscle weakness.
Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue.
Most types of MD are multi-system disorders with manifestations in body systems including the heart, gastrointestinal and nervous systems, endocrine glands, skin, eyes and other organs.Genetic causeThese conditions are inherited, and the different muscular dystrophies follow various inheritance patterns.
The best-known type, Duchenne muscular dystrophy (DMD), is inherited in an X-linked recessive pattern, meaning that the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes, and is thus considered sex-linked.
In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must generally be present in both copies of the gene to cause the disorder (relatively rare exceptions, manifesting carriers, do occur due to dosage compensation/X-inactivation).
Males are therefore affected by X-linked recessive disorders much more often than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
Diagnosis
The diagnosis of muscular dystrophy is based on the results of a muscle biopsy. In some cases, a DNA blood test may be all that is needed.A physical examination and the patient's medical history will help the doctor determine the type of muscular dystrophy.
Specific muscle groups are affected by different types of muscular dystrophy.Often, there is a loss of muscle mass (wasting), which may be hard to see because some types of muscular dystrophy cause a build up of fat and connective tissue that makes the muscle appear larger. This is called pseudohypertrophy.PrognosisThe prognosis for people with muscular dystrophy varies according to the type and progression of the disorder.
Some cases may be mild and progress very slowly over a normal lifespan, while others produce severe muscle weakness, functional disability, and loss of the ability to walk.
Some children with muscular dystrophy die in infancy while others live into adulthood with only moderate disability.
The muscles affected vary, but can be around the pelvis, shoulder, face or elsewhere.
Muscular dystrophy can affect adults, but the more severe forms tend to occur in early childhood.
Types
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- Becker's muscular dystrophy
- Congenital muscular dystrophy
- Duchenne muscular dystrophy
- Distal muscular dystrophy
- Emery-Dreifuss muscular dystrophy
- Facioscapulohumeral muscular dystrophy
- Limb-girdle muscular dystrophy
- Myotonic muscular dystrophy
- Oculopharyngeal muscular dystrophy
But there are more than 100 diseases in total with similarities to muscular dystrophy.
source: Wikipedia |
