Regulation of number and size of digits by posterior Hox genes: A dose-dependent mechanism with potential evolutionary implications

摘要

The proper development of digits, in tetrap- ods, requires the activity of several genes of the HoxA and HoxD homeobox gene complexes. By using a variety of loss- of-function alleles involving the five Hox genes that have been described to affect digit patterning, we report here that the group 11, 12, and 13 genes control both the size and number of murine digits in a dose-dependent fashion, rather than through a Hox code involving differential qualitative func- tions. A similar dose-response is observed in the morphogen- esis of the penian bone, the baculum, which further suggests that digits and external genitalia share this genetic control mechanism.