Developmental patterning genes and their conserved functions: From model organisms to humans

Molecular and genetic evidence accumulated during the past 20 years in the field of developmental biology indicates that different animals possess man y common genetic systems for embryonic patterning. In this review we descri be the conserved functions of such developmental patterning genes and their relevance for human pathological conditions. Special attention is given to the Hox genetic system, involved in establishing cell identities along the anterior-posterior axis of all higher metazoans. We also describe other co nserved genetic systems, such as the involvement of Pax6 genes in eye devel opment and the role of Nkx2.5-type proteins in heart development. Finally, we outline some fascinating problems at the forefront of the studies of dev elopmental patterning genes and show how knowledge obtained from model gene tic organisms such as Drosophila helps to explain normal human morphogenesi s and the genetic basis of some birth defects. (C) 2000 Academic Press.