A disorder where and enzyme (myeloperoxidase) deficiency which impairs the ability of the body's immune system to destroy invading bacteria and other pathogens. The condition may be due to inherited genetic anomalies or such things as lead poisoning, pregnancy, sepsis, lead poisoning and leukemias. Many patients are asymptomatic and symptomatic patients are more prone to serious fungal infections. See also Myeloperoxidase deficiency