The patients are prone to clinically significant infections caused by vaccination with the weakly virulent live-attenuated BCG, thus defining a form of syndromic Mendelian Susceptibility to Mycobacterial Disease (MSMD).61 The variants abolish CCR2 protein expression, CCR2-stimulated Ca2+ mobilization, ERK phosphorylation, monocyte migration, and CCL-2 clearance, resulting in high blood CCL-2 levels, but they do not alter monocyte-specific gene expression or functions, including phagocytosis and ROS production. This evidence concerns the gene CCR2 and Mendelian susceptibility to mycobacterial diseases.