Muscular dystrophy causes are attributed to defects in specific genes that code for muscle proteins. This genetic disease may be inherited from one or both parents. To get an insight on what causes muscular dystrophy, keep reading this article.
Muscular dystrophy, abbreviated as MD, is an umbrella term for a group of muscle related ailments. It is a chronic disease that slowly affects the mobility of a patient. Some forms of muscular dystrophy develop during childhood, whereas other types are diagnosed in adults and elderly people. One thing shared by all muscular dystrophy types is, they are inhered diseases. While most of us are not familiar with muscular dystrophy causes and symptoms, millions of people are afflicted with this debilitating disease.
What Causes Muscular Dystrophy?
Our muscles require a constant supply of proteins to remain in a healthy state and function normally. In a patient diagnosed with muscular dystrophy, there is lack of specific muscle proteins in the body. As a consequence, the muscles do not receive the required nutrients as they should, resulting in weakness and muscle loss with time. But, what is the root cause behind this lack of sufficient muscle proteins? Well, muscular dystrophy causes are genetic, meaning the genetic makeup of the patient is faulty.
Muscular Dystrophy Types and Causes
The defective gene responsible for causing muscular dystrophy is inherited from the parents, and is present at birth. Of course, symptoms of muscular dystrophy may appear at a later stage in life, depending upon the type of MD. Like several other hereditary diseases, the genetic defect identified for causing muscular dystrophy stems from gene mutation. Gene that has undergone mutation varies for each type of MD. Some of the commonly diagnosed muscular dystrophies and their causes are highlighted below.
Duchenne and Becker Muscular Dystrophy
As per the statistical record of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), they are prevalent in boys and seldom affect girls. Upon further researches, it is concluded that they are sex-linked recessive diseases. Over here, faulty gene present in X-chromosome is passed on from the mother to her son, who experiences this genetic disease. The gene that gets mutated codes for dystrophin (a protein found in the membrane of muscle fibers), and patients having it are unable to synthesize the same protein. The mother is the carrier of MD disease, and she may or may not show symptoms.
Myotonic Muscular Dystrophy
This is a form of autosomal dominant pattern of inheritance. In myotonic muscular dystrophy (MMD), mutation occurs in the gene that codes for kinase protein. In a healthy individual, triplet repeat sequence (short repeats in the DNA stretch) is present. If this sequence is repeated many times, production of kinase and other muscle proteins are hindered. The severity of myotonic muscular dystrophy symptoms depends on how many times the gene sequence is repeated. If repetitive copies are less, symptoms are less severe, and vice versa.
Limb-Girdle Muscular Dystrophy
Limb-girdle muscular dystrophy, or simply LGMD, is inherited from one or both parents. In autosomal dominant pattern of inheritance, a copy of mutated gene is received from one parent, and symptoms appear at adulthood stage. In case of autosomal recessive cases, a copy of defective gene is passed on from both the parents, and symptoms are presented either in childhood or teenage stage. Of these, recessive LGMD occurs more frequently than the dominant type. There are over 30 types of this particular muscular dystrophy.
Facioscapulohumeral Muscular Dystrophy
This type of muscular dystrophy affects both males and females, usually in their teenage years. Diagnosed in 5 out of 100,000 people, muscle weakness symptoms of facioscapulohumeral muscular dystrophy (FSHD) are concentrated in the face, arm, shoulder and upper portion of the body. The pattern of inheritance is identified as autosomal dominant, i.e. it can be inherited from one of the parents. Some patients show serious symptoms, and at times, they lose the ability to move independently.
Oculopharyngeal Muscular Dystrophy
The oculopharyngeal muscular dystrophy shows both patterns of autosomal inheritance – dominant and recessive. In case of dominant inherited case, the abnormal gene is inherited from one of the parents. While recessive oculopharyngeal muscular dystrophy is caused due to passing of defective gene from both the parents. Though the genetic defect is congenital, it is minor and notable symptoms are presented when the afflicted person turns 40 years or older.
Congenital Muscular Dystrophy
This type of MD is named after the age, which marks the onset of symptoms. And as the name clearly suggests, congenital muscular dystrophy is diagnosed in babies. The characteristic symptoms are general muscle weakness, which may or may not be accompanied with joint deformities and brain malfunctions. In this form of MD, both types of autosomal inheritance patterns are observed. Thus, patients may have only one of two copies of the defective gene. Generally, the life expectancy is short for patients having this severe disorder.
Thus, muscular dystrophy causes are specific for each form of MD. One of the disheartening muscular dystrophy facts is, there is no cure for this genetic disorder. Medical researches are ongoing to ravel genetic therapy to correct mutated genes, which are causing muscular dystrophy. Treatment for the same is focused on addressing joint deformities, improving mobility and increasing the longevity of afflicted patients.