Genetic variants causing G6PD deficiency: Clinical and biochemical data support new WHO classification.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency in erythrocytes causes acute haemolytic anaemia upon exposure to fava beans, drugs, or infection; and it predisposes to neonatal jaundice. The polymorphism of the X-linked G6PD gene has been studied extensively: allele frequencies of up to 25% of different G6PD deficient variants are known in many populations; variants that cause chronic non-spherocytic haemolytic anaemia (CNSHA) are instead all rare. WHO recommends G6PD testing to guide 8-aminoquinolines administration to prevent relapse of Plasmodium vivax infection. From a literature review focused on polymorphic G6PD variants we have retrieved G6PD activity values of 2291 males, and for the mean residual red cell G6PD activity of 16 common variants we have obtained reliable estimates, that range from 1.9% to 33%. There is variation in different datasets: for most variants most G6PD deficient males have a G6PD activity below 30% of normal. There is a direct relationship between residual G6PD activity and substrate affinity (Km G6P ), suggesting a mechanism whereby polymorphic G6PD deficient variants do not entail CNSHA. Extensive overlap in G6PD activity values of individuals with different variants, and no clustering of mean values above or below 10% support the merger of class II and class III variants.

Glucose-6-Phosphate Dehydrogenase Deficiency.

G6PD is a housekeeping gene expressed in all cells. Glucose-6-phosphate dehydrogenase (G6PD) is part of the pentose phosphate pathway, and its main physiologic role is to provide NADPH. G6PD deficiency, one of the commonest inherited enzyme abnormalities in humans, arises through one of many possible mutations, most of which reduce the stability of the enzyme and its level as red cells age. G6PD-deficient persons are mostly asymptomatic, but they can develop severe jaundice during the neonatal period and acute hemolytic anemia when they ingest fava beans or when they are exposed to certain infections or drugs. G6PD deficiency is a global health issue.

Alternative splicing variants of carbonic anhydrase IX in human non-small cell lung cancer.

In human cancers, carbonic anhydrase IX (CAIX) contributes to maintain intracellular and extracellular pH under hypoxic conditions, but also influences regulation of cell proliferation and tumor progression. CaIX was previously indicated as an independent prognostic marker in non-small cell lung carcinoma (NSCLC). Very recently a CAIX alternative splicing isoform, generating a transcript lacking of exons 8-9, was detected in cancer cells independently from the levels of hypoxia. This alternative splicing (AS) generates a truncated protein lacking the transmembrane region, the intracellular tail and the C-terminal of the catalytic domain and competes with the full-length (FL) isoform in the regulation of the extracellular pH, mainly in a mild hypoxic status. In the present study we measured the mRNA expression of FL and AS CAIX isoforms in 101 NSCLC and in paired not affected tissues. The two isoforms were coexpressed in all NSCLC and normal tissues but while AS mRNA was prevalent in normal tissues (66+/-3%), the FL isoform was higher in NSCLC (58+/-2%, p=0.001). FL mRNA, but not AS, was statistically increased in NSCLC (p=0.01) and showed a statistical association with lymphnode involvement (p=0.009) and tumor stage (p=0.04). Global survival analysis of cancer/related death showed that high levels of FL mRNA were predictive of unfavorable outcome (p<0.0001) and shorter disease-free survival (p<0.0001). Multivariate analysis indicated that FL is an independent prognostic factor for overall survival and higher levels of mRNA in NSCLC sensibly increase hazard ratio ( approximately sixfold). In conclusion, our results seems to indicate that, at least in NSCLC, FL CAIX is the most accurate surrogate of hypoxic stress and represents the only variant with a prognostic role. These data indicate the importance of a separate measurement of the two isoforms in cancer and the need of an accurate re-evaluation of most studies on the clinical role of CAIX in cancer diagnosis.