Identification of an X-linked member of the Odc gene family in the mouse.

The mouse ornithine decarboxylase gene is part of a dispersed family of at least 14 related loci (1.2). Eight Odc loci have been assigned to 7 different autosomes (3,4), although the actual structural locus has not been identified. Recent mapping of the mouse genome has exploited the sequence diversity apparent between inbred strains and feral species, notably Mus spretus (5). This diversity, expressed as restriction fragment length polymorphism, together with the unique segregation pattern of X-linked loci, has facilitated assignment of molecular markers to the mouse X chromosome (6). Figure 1 shows how Fl progeny from reciprocal crosses between C57BL/6JRos (B) and wild-derived M. musculus from Denmark (D) have been used to identify an X-linked member of the Odc gene family. This assignment demonstrates the power of the mapping technique, as a single X-linked band can be distinguished from multiple autosomal bands.