Why is duchenne muscular dystrophy almost never seen in girls?
It all comes down to the X chromasome. The Role of the X chromosome 1. Duchenne Muscular Dystrophy is a disorder due to a mutation with in the X chromosome where the dystrophin gene resides. 2. Girls do not get this disorder because they have two X chromosomes. Therefore if one of the X chromosomes has a mutation, and the dystrophin gene is unable to work properly the dystrophin gene in the other X chromosome will “take over”. However, boys only have one X chromosome (the other chromosome is a Y chromosome which does not contain the dystrophin gene) and therefore do not have another X chromosome to fall back on. 3. The boy receives the mutated X chromosome from his mother 4. A boy can also get Duchenne’s if the gene mutates within the mothers egg or early in the embryo’s development. (approximately 1/3 of boys get Duchenne’s this way) 5. A girl can get the mutated gene as well and pass it on to her future sons 6.
