Mendelian Susceptibility to Mycobacterial Disease with Signal Peptide Peptidase-like 2A (SPPL2A) Deficiency: A Case Report.

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare genetic disorder characterized by immunodeficiency, leading to increased susceptibility to mycobacterial infections. Studies have identified several genes that are associated with MSMD in the interferon-gamma/interleukin (IL)-12/IL-23 signaling pathway. One of these genes is signal peptide peptidase-like 2A (SPPL2A), which is very rare, and defects in this gene have been reported only in 3 patients with MSMD. This case report presents the rare SPPL2A deficiency with an abnormal presentation, which adds to the limited number of these genetic defects. This report presents the case of a 1-year-old boy who developed Bacillus Calmette-Guerin infection (BCGitis), lymphadenopathy, and an arm abscess that required surgical drainage following BCG vaccination. The patient had hypogammaglobulinemia, normal B-cell counts, normal CD4 counts, low CD8 counts, and SPPL2A deficiency, which is related to MSMD. The patient received a second line of anti-tuberculosis agents. SPPL2A deficiency is associated with MSMD and can cause severe BCGitis and disruption of immunoglobulin production.