trophy (mdx) in the mouse

An X chromosome-linked mouse mutant (gene symbol, mdx) has been found that has elevated plasma levels of muscle creatine kinase and pyruvate kinase and ex- hibits histological lesions characteristic of muscular dystro- phy. The mutants show mild clinical symptoms and are viable and fertile. Linkage analysis with four X chromosome loci in- dicates that mdx maps in the Hq Bpa region of the mouse X chromosome. This gives a gene order of mdx-Tfm-Pgk-l-Ags, the same as for the equivalent genes on the human X chromo- some. There are two major forms of X chromosome-linked muscu- lar dystrophy in man: Duchenne (McKusick number, 31020) and Becker (McKusick number, 31010) (1-3); recent linkage analyses with restriction fragment-length polymorphisms suggests that they could be allelic (4, 5). For neither of these syndromes is the primary lesion or a homologous animal