STAT1 and osteomyelitis: We report a novel de novo heterozygous missense mutation in exon 23 of the STAT1 gene (NM_007315.4):c.2129C>T(p.Ser710Phe) (S710F), located in the transactivation domain (TAD) for two Chinese siblings, whereby the index patient presented with multifocal osteomyelitis after Bacillus Calmette–Guerin (BCG) vaccine, while the younger sibling was spared the infection, as BCG vaccination was withheld at birth.