Duchenne Muscular Dystrophy is actually caused by a mutation in a particular gene within the X-chromosome. This aforementioned gene houses the coding that is required to create an important protein in our body known as dystrophin. Dystrophin is a large, rod-like protein that is responsible for strengthening muscle fibres so they don’t tear when they undergo regular use. Those with muscular dystrophy cannot create this protein in their muscles, resulting in them having extremely delicate muscle cells. (DMD Gene, 2016)
As stated earlier, this disorder is often appears in a patient because they inherited it from their parents. The most common scenario is that the mother is a “carrier”, which means that they have an X-chromosome with the dystrophin mutation. According to the Muscular Dystrophy Association, each son that is born from a carrier has a fifty percent chance of inheriting said affected chromosome, thus causing the son to develop DMD. A father with DMD cannot pass on his disorder directly to the next generation due to the fact that he would pass down his Y-chromosome to the son rather than his affected X-chromosome (males require an x-chromosome from the mother and a Y-chromosome from the father). That being said, the father can pass down his affected X-chromosome to a daughter, thus creating a carrier (or a female DMD patient in extremely rare cases). On rarer occasions, the patient’s own X-chromosome underwent a mutation that affected the dystrophin gene. In any case, the son of a person with DMD cannot inherit it, as the X-chromosome is taken from the mother. However, it is possible that they can produce a female offspring that is a carrier. (DMD - Causes/Inheritance, n.d.)
Background Image 3. Digital image of X Chromosomes. Chromosome X [Digital image]. (n.d.). Retrieved April 12, 2016, from http://interrete.org/wp-content/uploads/2016/01/chromosome-X-1050x763.jpeg