Limits to the use of the glucose 6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase index for the detection of glucose 6-phosphate dehydrogenase deficiency

Rasburicase-induced Methemoglobinemia: A Case Report and Literature Review

Rasburicase is a recombinant urate oxidase enzyme indicated for tumor lysis syndrome, a potential life-threatening oncologic emergency that occurs most commonly during initial chemotherapy for hematological malignancies. As a result of the defects in the physiological antioxidant pathway, erythrocytes of patients with glucose-6-phosphate dehydrogenase deficiency are not protected against the oxidizing stress exerted by hydrogen peroxide generated with the administration of rasburicase. The authors report a 14-year-old patient, diagnosed with T-cell acute lymphoblastic leukemia, who developed methemoglobinemia and hemolytic anemia with low oxygen saturation after starting steroids, hyperhydratation, and rasburicase administration. The complications resolved with supportive therapy only.

Glucose-6-phosphate dehydrogenase deficiency in Italian blood donors: prevalence and molecular defect characterization

BACKGROUND

In the countries with high G6PD deficiency prevalence, blood donors are not routinely screened for this genetic defect. G6PD deficiency is often asymptomatic, blood donors may be carriers of the deficiency without being aware of it. The aim of the study was to evaluate the prevalence of G6PD deficiency among the Italian blood donors.

DESIGN AND METHODS

From October 2009 to April 2011, 3004 blood donors from a large hospital transfusion centre were screened for G6PD deficiency using differential pH-metry and the characterization of G6PD mutations was performed on G6PD-deficient subjects. The haematological features of G6PD-deficient and normal donors were also compared.

RESULTS

Thirty-three subjects (25 men and 8 women) with low G6PD activity were identified, corresponding to 1·1% of the examined blood donor population. The frequencies of class II severe alleles (Mediterranean, Valladolid, Chatham and Cassano) and class III mild alleles (Seattle, A- and Neapolis) were 48% and 43%, respectively. The haematological parameters of G6PD- donors were within normal range; however, the comparison between normal and G6PD- class II donors showed significant differences.

CONCLUSION

In Italy, the presence of blood donors with G6PD deficiency is not a rare event and the class II severe variants are frequent. The identification of G6PD-deficient donors and the characterization of the molecular variants would prevent the use of G6PD-deficient RBC units when the haemolytic complications could be relevant especially for high risk patients as premature infants and neonates and patients with sickle cell disease submitted to multiple transfusions.

Glucose-6-phosphate dehydrogenase laboratory assay: How, when, and why?

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common defect of red blood cells. Although some different laboratory techniques or methods are employed for the biochemical screening, a strict relationship between biochemists, clinicians, and molecular biologists is necessary for a definitive diagnosis. This article represents an overview on the current laboratory tests finalized to the screening or to the definitive diagnosis of G6PD-deficiency, underlying the problems regarding the biochemical and molecular identification of heterozygote females other than those regarding the standardization of the clinical and laboratory diagnostic procedures. Finally, this review is aimed to give a flow-chart for the complete diagnostic approach of G6PD-deficiency.

Frequency of butyrylcholinesterase gene mutations in individuals with abnormal inhibition numbers: an Italian-population study

OBJECTIVES

More than 30 genetic variants of serum cholinesterase (butyrylcholinesterase, BChE) have been described. Some of them (the atypical and the fluoride-resistant variants) are well known because carriers are prone to develop prolonged apnea following the administration of the muscle relaxant succinylcholine. Genotype characterization is therefore important in order to prevent such episodes. Genetic studies have so far focused on selected individuals or families rather than on the random population.

METHODS

From a large group of healthy blood donors (n = 2609), we selected all the 58 individuals with low serum cholinesterase activity: among them 28 subjects had abnormal dibucaine and fluoride inhibition numbers. Twenty-five mutations in the coding region of the human cholinesterase gene were analyzed.

RESULTS

All individuals with abnormal inhibition numbers were homozygotes or double heterozygotes in several mutations. Asp70Gly (Atypical variant) and Ala539Thr (K variant) were the most frequently observed amino acid substitutions. The majority of subjects with low BChE activity but normal dibucaine and fluoride number presented only the K form. We analyzed 106 randomly chosen subjects for K and atypical variants. Carriers of these alleles were at risk of low BChE activity (OR = 9.55, 95%CI, 5.61-16.26 and OR = 30.33, 95%CI, 7.05-130.52 respectively).

CONCLUSIONS

Data obtained from this study help to better define the etiology of low BChE activity and the role of the rather common K allele. It is the first time that such a large population has been screened for so many mutations. BChE is also implicated in detoxifying cocaine; therefore genetic analysis could be useful in cases of cocaine toxicity in Italian subjects.