Finally, all the cells in the animals used in this study were mutant, and thus, it is difficult to know whether some of the effects on regeneration might have been caused, at least in part, by systemic effects of the mutations on fin regeneration, rather than local requirements for those genes on these processes; this is especially the case with the duox mutants, which we know can have systemic effects, including hypothyroidism. The gene discussed is DUOX1; the disease is hypothyroidism.