Notably, M. tuberculosis phoP mutants display pleiotropic phenotypic effects including impaired secretion of ESX-1 substrates [7], compromised production of sulphatides (SL), diacyltrehaloses (DAT) and polyacyltrehaloses (PAT) [8] and reduced virulence in the macrophage and mouse models of infection [4], [5]. The gene discussed is ESX1; the disease is infection.