HORIBA expands its clinical chemistry assay menu with the addition of the POINTE brand. Among these assays is the POINTE Glucose-6-Phosphate Dehydrogenase (G6PD) test—an important and unique offering for clinical chemistry.
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Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme that is critical to preventing cellular damage from reactive oxygen species. G6PD Deficiency is the most common known human enzyme defect, impacting more than 500 million people globally.1
G6PD is an X-linked mutation, and therefore genetic males are more commonly affected by the disease than genetic females. Hemizygous, Homozygous, and heterozygous individuals can all show different levels of severity.
All carrier boys are affected, while most girls escape deficiency due to X lyonization.
Hemizygous boys and homozygous girls typically show similar residual enzyme activity.
Heterozygous girls show a wide range of measured activity, indicating abnormalities in lyonization, which is no longer random but biased toward either the wild-type or the deficient allele.
Table 1: 2024 WHO classification of glucose-6-phosphate dehydrogenase variants9
| G6PD variant class | Median G6PD activity (% of normal) | Associated clinical manifestations |
| A | < 20%a | Chronic hemolytic anemia |
| B | < 45% | Neonatal jaundice; acute hemolytic anemia triggered by certain medicines, fava beans or infection |
| C | > 60% | No hemolysis |
| Ub | Any | Uncertain clinical significance |
a A variant with < 20% activity will be in class A only if it is associated with chronic hemolytic anemia. If a variant with < 20% activity is associated with acute hemolytic anemia induced by fava beans, drugs or infection it will be in class B; if clinical manifestations are unknown, it will be in class U.
b A temporary assignment for variants for which there is currently insufficient information regarding clinical manifestations.
This particularity explains why up to 25% of heterozygous girls (Variant Class B) are unrecognized in rapid enzyme tests. Therefore, G6PD phenotype accurate quantitative enzyme activity testing is mandatory to identify these individuals.
G6PD deficiency is the most common enzymatic blood disorder worldwide. In certain regions, its occurrence can be as high as 20% of the population. The highest rates are found in tropical Africa, where more than 24% of individuals are carriers. In the United States, up to 24% of African-American individuals are affected, and the deficiency accounts for approximately 30% of neonatal kernicterus cases. In France, an estimated 450,000 people are affected, with around 150,000 high-risk births and 9,000 children with the deficiency each year.
Ruwende C, Hill A. Glucose-6-phosphate dehydrogenase deficiency and malaria. J Mol Med. 1998;76:581-8.
Some researches suggest that individuals with G6PD Deficiency have some protection from malaria, which may explain its high prevalence in populations from Africa, the Mediterranean, Asia, and tropical/subtropical regions².
There are several important reasons to test for G6PD deficiency, primarily to avoid exposure to the many potential triggers that may cause hemolytic crisis in affected individuals. Common triggers of hemolytic anemia include Rasburicase, Vitamin K, sulfa drugs, quinolones, nitrofurantoin, aspirin, primaquine or tafenoquine, penicillamine, and fava beans5. The World Health Organization recommends G6PD testing to ensure the safe administration of primaquine or tafenoquine for the prevention of Plasmodium vivax and P. ovale malaria relapses.
Early diagnosis, particularly in newborns, enables healthcare providers to educate parents on the triggers that may cause hemolytic crisis. The genetic and biochemical characterization of G6PD variants and their genotype-phenotype correlation are relevant to understanding the risk for hemolysis and hyperbilirubinemia in the G6PD deficient neonate.
Since G6PD activity may shift throughout an individual's life, periodic testing is important to determine current severity levels. This is particularly critical in oncology settings, where knowing a patient’s exact G6PD activity level before initiating treatments such as chemotherapy or Rasburicase can help prevent severe adverse reactions.
The POINTE Glucose-6-Phosphate Dehydrogenase assay provides a quantitative determination of G6PD activity in blood. Activity units are reported relative to the hemoglobin concentration in the blood, in activity units/gram Hemoglobin.
The POINTE G6PD Reagent Set can be applied to a variety of clinical chemistry analyzers, including the Pentra C400, Yumizen C230, Yumizen C240, and Yumizen C560. The sample preparation includes only a single 5 minute lyse step and can even be automated on some systems.
For more about HORIBA POINTE clinical chemistry reagent brand, click here.
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