Taken together, many CS-associated developmental defects have been accurately recapitulated in mice and zebrafish, but not yet in Drosophila. Of note, these models express a constitutively active allele of HRAS, which is not the most common CS-causing allele of HRAS, which is just strongly activating (Sol-Church and Gripp, 2009). The gene discussed is HRAS; the disease is Cowden syndrome 1.