Deficiencies in T-cell immunity are the main predisposing factor for PCP, and patients at increased risk of infection include those with severe combined immunodeficiency, HIV, CD40 ligand deficiency, nuclear factor κB (NF-κB) essential modulator (NEMO) deficiency, hyperimmunoglobulin E syndrome (hyper-IgE) (Job syndrome), and X-linked hyperimmunoglobulin M syndrome [124, 125]. The gene discussed is IGHE; the disease is hyperinsulinemic hypoglycemia, familial, 4.