[Genetics of the limb pattern formation in mouse].

Genetics studies using mouse mutants have revealed key functions of several genes in limb development. In this review, I summarized approaches of forward genetics to elucidate genetic control of mouse limb development based on mouse limb mutants. In mouse, there are many mutants that exhibit malformation in distal elements (autopod) of limb, i.e. polydactyly and ectrodactyly. Some of them are reported as failure in the generation and maintenance of axes in limb development. Recent advance in genome analysis has allowed us to identify and clone the causative gene of mouse mutants by positional cloning technique. In addition, analysis of expression patterns of marker genes that play key roles in limb development gives some hints with respect to the functions of the affected genes. In many cases, the same mutants show different manifestations of the phenotype on different genetic backgrounds, indicating the presence of the second gene that may genetically interact with the original mutant gene. This also affords very useful opportunity to study epistatic interaction of genes involved in the relevant phenotypes. Thus, all these approaches of forward genetics facilitate to understand the genetic control of limb development of mouse.