However, recent studies using two or more mast cell-deficient Kit mutant mouse strains and/or mutant mouse strains with unperturbed c-Kit function revealed a more complicated picture: depending on the nature of the mutation resulting in a mast cell deficiency as well as the type and severity of infection, mast cells can have no effect, aggravate, or attenuate inflammation and infectious disease severity (25–28). The gene discussed is KIT; the disease is infection.