The amino-terminal region of the Hog domains, encode two unique domains, termed wart and ground. Genes have also been identified that encode wrt and grd but not the Hog domain, hence termed warthog (wrt) and groundhog (grd). Sequence and phylogentic analyses of the amino- and carboxy-terminal domains reveal an evolutionary relationship, thus the nematode genes are monophyletic derivatives of a common ancestor - synonymous with the Hh genes.
Parts showing similarity in both structure and function to intein domains in prokaryotes are termed Hint domains (Hedgehog/intein). No Hint domains, however, have yet been found in C. elegans. Its now possible to find these sequences in the C. elegans genome.
