Figure 3.

The most parsimonious genetic network of the M. tuberculosis Beijing genotype based on MIRU-VNTR data. MIRU alleles (no. of copies per locus) for MIRU types are shown in the Supplemental Table. Each arm in the network represents one event (one change per locus). Circle size is roughly proportional to the number of strains. Numbers inside circle segments are the percentage of strains of a given type of all strains from the same area. Dotted branches depict possible alternatives. Question mark means intermediate node in which no strain was found in our database. In 2004, Sun et al. who reported Beijing strains from Singapore suggested that the majority of the Singaporean population is of Chinese descent and that tuberculosis mainly affects the elderly, many of whom are first- or second-generation immigrants from mainland China. We therefore designated the Beijing genotype strains from Singapore as Chinese.