A novel mutation of the IL12RB1 gene in a child with nocardiosis, recurrent salmonellosis and neurofibromatosis type I: first case report from Thailand.

Genetic defects of interleukin (IL)-12/23-and interferon (IFN)-γ-mediated immunity can cause in-creased susceptibility to intracellular microbes. Among these defects, a mutation of the gene encoding the IL-12 receptor β1 (IL-12Rβ1) is the most common worldwide. A 12-year old Thai boy with pre-existing neurofibromatosis type 1 (NF1) was evaluated for primary immunodeficiency after a history of tuberculous lymphadenitis, recurrent Salmonella infections and nocardiosis. Flow cytometry of phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMCs) revealed a defect in the IL-12Rβ1 surface expression. A genetic study showed a novel nonsense homozygous mutation of the IL12RB1 gene in exon 4 (402C>A), confirming the diagnosis of IL-12Rβ1 deficiency. This is the first case report of a primary IL-12Rβ1 deficiency in Thailand with the interesting finding of a coexisting NF1.