Significantly higher frequency of the MspI 2.2 kb allele of the Duchenne muscular dystrophy intragenic probe P-20 in the Chinese population.

The P-20 intragenic marker was used to test for restriction fragment length polymorphisms in unrelated Chinese patients with Duchenne or Becker muscular dystrophy or X-linked mental retardation. In addition to polymorphism at the 6.0/3.5 kb MspI allelic site, we found an independent and high frequency of polymorphism at the 2.2/1.8 kb site. This differs from results found with other populations.