Direct DNA sequencing of all exons and exon-intron boundaries of all known disease genes of MSMD, the IL12RB1 gene in Patient 1 carry two heterozygous mutations, a missense mutations (c.635G > A, R212Q) and a deletion mutation (c.765delG) (Fig 2A). This evidence concerns the gene IL12RB1 and Mendelian susceptibility to mycobacterial diseases.