A genetic variant of Mendelian susceptibility to mycobacterial disease with characteristics of mild bacillus Calmette-Guérin (BCG) infections and recurrent Salmonella infections. The prevalence is unknown. The disease presents in early childhood. BCG is the most common infection encountered, usually after receiving the vaccination. Non-typhoidal Salmonella infections are also seen in half of all cases. Caused by homozygous mutations in the IL12B gene on chromosome 5q31.1-q33.1 which encodes for the IL-12p40 subunit. There are 9 different IL12B mutant alleles identified, including 2 small insertions, 3 small deletions, 2 splice site mutations, 1 large deletion and 1 nonsense mutation.