G6PD Deficiency - Prevalent and Under-Recognized Disease

Abstract

The Glucose-6-Phosphate- Dehydrogenase (G6PD) Deficiency is a chromosome-X linked disorder, affecting about 400 to 500 million people worldwide, with several clinical presentations and this enzyme represents an import role in hexose monophosphate path and production of glutathione inside the red blood cell, as a protective agent against oxidant substances.

      Their genetic etiology is localized in the long arm of the X-chromosome in the region 28, with greater severity registered in males than females, as this sex don’t have a complete deficiency of this enzyme.

       The sequence of events that follows after the oxidant agent contact and glutathione decrease are the methaemoglobin production;globin denaturation and the Heinz Corpuscles formation on red cell membrane, resulting in hemoglobin leaking and as main event, hemolysis with destruction in the reticuloendothelial system.

        Clinical manifestations are wide, depending on degree of enzyme deficiency, the majority are asymptomatic, without anemia or cell destruction, but, it may occur a life-shortening of half-life in red blood cell, however, acute hemolysis can be triggered by medications;foods, mainly fava, a type of bean consumed in Middle East, and infections, with this event occurring commonly in mediterranean variant than in A, described in Introduction. 

Their classical presentation is from a patient after primaquine intake, medication for malaria infection, with highlight for G6PD A variant, mainly present for african-descendant individuals, symptomatic with jaundice;pallor and dark-urine, associated by hemoglobin fall, other contraindicated medications are antibiotics from Fluoroquinolone class (ciprofloxacin;moxifloxacin and norfloxacin);methylene blue;sulphonylurea like glipizide and glibenclamide, medications used for type-2 diabetes treatment and anti-uremic medication like rasburicase. 

Diagnostic tests can be qualitative or quantitative, for screening or confirmatory tests, like the direct antiglobulin; the G6PD activity rate and reduction of NADP;the production of NADPH in spectrophotometric method, in which this last test is a confirmatory way to diagnose the pathology, indications for the tests are: jaundice evaluation or hemolytic anemia without an specific cause;asymptomatic patients with high risk of deficiency before drugs administration or family members of an affected individual. 

This narrative review of literature proposes to offer a general panel about the pathology, as well about epidemiology and complications, because of their diet;medications and pathologies limitations that can cause hemolysis, additionally as Brazil is an endemic country for malaria and their medications also can cause hemolysis, it is important to do the health promotion and stimulate the disease importance to  get better resources for testing.