DNA is a chemical component of the cell, which stores and propagates information in the form of sets of the nucleotide sequence, genes. The gene information is expressed as proteins which perform various functions in and around the cells. Any inappropriate alternations such as insertions, deletions, replacements, and other mutations in the nucleotide sequence lead to the production of defective proteins or complete loss of particular protein production and this causes disorders (Mutations, 2015). These alterations are either inherited from the ancestors or produced due to DNA damage and improper DNA repair. The type and severity of a disorder or disease depend on the type, importance, and degree of the DNA damage or defect in the protein (Hogan, 2010; Mutations, 2015).
Several proteins function towards the maintenance of muscle tissue. Any defects in the function or production of these proteins cause damage to the muscle and leads to a group of disorders called muscular dystrophies. Approximately half of the muscular dystrophies are associated with the loss of protein, and dystrophin function due to its role in muscle structure (Culligan, Mackey, Finn, Maguire & Ohlendieck, 1998). Inherent mutations are responsible for most of the muscular dystrophies in which, mutations in x-linked genes are dominated affecting mostly males; for example, Duchenne muscular dystrophy, and Emery–Dreifuss muscular dystrophy. Some types of muscular dystrophy are associated with long repeats of tri- or tetranucleotides that produce long RNA transcripts and impaired muscle proteins; for example, CTG repeats in myotonic dystrophy protein kinase gene associated with Myotonic muscular dystrophy. A small portion of muscular dystrophies are due to spontaneous DNA damage, errors during DNA replication or impaired DNA repair (Choices NHS, 2017). Also, longer DNA sequence of a gene makes it more vulnerable to mutations; for example, dystrophin gene, which is over 2.4 x 106 nucleotides in length (Mutations, 2015).