is an umbrella term used to describe any of the inherited disorders which result in the degeneration of muscle mass and therefore muscle activity. There are various types of MD, which affect different factors such as the- age of onset, rate of progression and distribution of the weakness. For example MD can be localized to a specific area whilst in other types MD can be overall across the whole body. Those with MD are usually unable to walk by the age of 12 and frequently die from compli