Genetics of limb development and congenital hand malformations.

The vertebrate limb bud develops along three different axes: proximodistal, anteroposterior, and dorsoventral. Several genetic factors responsible for control of each of the three limb axes have been identified. The genes involved interact in complex feedback loops to achieve proper arrangement and differentiation of tissues. Most of the available information on limb development and patterning has come from studies carried out in the lower vertebrates. In recent years, an increasing number of studies have been unraveling the genetic basis of human hand malformation phenotypes. At present, genes responsible for preaxial polydactyly, split hand/split foot malformation, and brachydactyly type C have been localized, and the gene responsible for synpolydactyly has been identified. In this paper, we present an overview of the genetic factors involved in limb development, followed by summarized discoveries in the genetics of human congenital hand malformations.