It says in one of the books that Duchenne MD and Becker MD are caused by the same gene, how come they are so different?
BMD muscle stained for dystrophin. They are caused by differently mutated alleles of the same gene. Both types of mutation are recessive and X-linked. In DMD the boys seldom walk after 11 or 12 years. Men with Becker may walk well into adult life. The difference is that the mutated BMD gene is able to produce small amounts of abnormal dystrophin. We will return to the molecular basis of this in third year! Note not only the prescence of some dystrophin but the fact that the muscle fibres have a more normal shape than in DMD. X-inactivation.
