Duchenne muscular dystrophy

In Duchenne muscular dystrophy, several affected females
had been reported who had one X chromosome disrupted by
an X:autosome translocation with the normal X chromosome
being preferentially inactivated. The site of the break point in
these cases was always on the short arm of the X chromosome
at Xp21, which suggested that this was the location of the gene
for DMD. DNA variations in this region, identified by
hybridisation with DNA probes, provided markers that were
shown to be linked to the gene for DMD in family studies in
1983. Strategies were then developed to identify DNA
sequences from the region of the gene for DMD, some of which
were missing in affected boys indicating that they represented
deleted intragenic sequences. The entire gene for DMD was
subsequently cloned in 1987 and its structure determined.