Do multigene families regulate vertebrate development?

The identification of mammalian gene families sharing protein domains with genes that regulate Drosophila embryogenesis could prove to be a major stepping stone towards understanding the genetic basis of mammalian development. Three types of multigene families have already been identified whose expression patterns during embryogenesis are strikingly different from one another. Evidence is accumulating that these multigene families may participate in pattern formation and segmentation of the mammalian embryo