Myeloperoxidase deficiency

Myeloperoxidase deficiency
Classification and external resources
Hypochlorous acid is normally produced by myeloperoxidase
OMIM	254600
DiseasesDB	8662
eMedicine	ped/1530

Myeloperoxidase deficiency is a common genetic disorder featuring deficiency, either in quantity or function, of myeloperoxidase, an enzyme found in certain phagocytic immune cells, especially polymorphonuclear leukocytes.

It can appear similar to chronic granulomatous disease on some screening tests.^[1]

Presentation

Although MPO deficiency classically presents with immune deficiency (especially candida albicans infections), the majority of individuals with MPO deficiency show no signs of immunodeficiency.

The lack of severe symptoms suggest that role of myeloperoxidase in the immune response must be redundant to other mechanisms of intracellular killing of phagocytosed bacteria.^[2]

Patients with MPO deficiency have a respiratory burst with a normal nitro blue tetrazolium (NBT) test because they still have NADPH oxidase activity, but do not form bleach due to their lack of myeloperoxidase activity. This is in contrast to chronic granulomatous disease in which the NBT test is 'positive' due to the lack of NADPH oxidase activity (positive test result means neutrophils fail to turn blue).

References

1. ^ Mauch L, Lun A, O'Gorman MR, et al. (May 2007). "Chronic granulomatous disease (CGD) and complete myeloperoxidase deficiency both yield strongly reduced dihydrorhodamine 123 test signals but can be easily discerned in routine testing for CGD". Clin. Chem. 53 (5): 890–6. doi:10.1373/clinchem.2006.083444. PMID 17384005. http://www.clinchem.org/cgi/pmidlookup?view=long&pmid=17384005. 
2. ^ Levinson, Warren. "Medical Microbiology & Immunology, 8th ed." Lange:2004.