Duchenne is caused by a mutation on the X chromosome, which results in partial or complete inability to produce the muscle protein, dystrophin. Duchenne muscular dystrophy is inherited in an X-linked recessive pattern.
Males have only one copy of the X chromosome, which they receive from their mother. If their X chromosome has a DMD gene mutation that prevents the instructions contained in the gene from being understood, they will Duchenne muscular dystrophy.
Females, on the other hand, have two copies of the X chromosomes. Since females have two copies of this gene, if one copy does not work, they have a back-up copy to produce the dystrophin protein.
Although Duchenne is thought of as an inherited condition, more than 30% of cases result from a spontaneous mutation.
The mutations delete part of the gene, abnormally duplicate part of the gene, or change a small number of nucleotides in the gene.