G6PD deficiency from lyonization after hematopoietic stem cell transplantation from female heterozygous donors

Population screening for glucose-6-phosphate dehydrogenase deficiency using quantitative point-of-care tests: a systematic review

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked hereditary disorder and a global public health concern that is most prevalent in malaria-endemic regions including Asia, Africa, and the Mediterranean. G6PD-deficient individuals are at high risk of developing acute hemolytic anemia following treatment with antimalarial drugs including Primaquine and Tafenoquine. However, the currently available tests for G6PD screening are complex and often have been misclassifying cases, particularly for females with intermediate G6PD activity. The latest innovation of quantitative point-of-care (POC) tests for G6PD deficiency provides an opportunity to improve population screening and prevent hemolytic disorders when treating malaria. Aim(s): To assess the evidence on the type and performance of quantitative point-of-care (POC) tests for effective G6PD screening and hence, radical elimination of Plasmodium malaria infections. Methods: Relevant studies published in English language confined from two databases, Scopus and ScienceDirect were searched from November 2016 onwards. The search was conducted using keywords including "glucosephosphate dehydrogenase" or "G6PD", "point-of-care", "screening" or "prevalence", "biosensor" and "quantitative". The review was reported following the PRISMA guidelines. Results: Initial search results yielded 120 publications. After thorough screening and examination, a total of 7 studies met the inclusion criteria, and data were extracted in this review. Two types of quantitative POC tests were evaluated, namely, the CareStart^TM Biosensor kit and the STANDARD G6PD kit. Both tests showed promising performance with high sensitivity and specificity ranging mostly from 72% to 100% and 92%-100%, respectively. The positive and negative predictive values (PPV and NPV) ranged from 35% to 72% and 89%-100%, with accuracy ranging from 86% to 98%. Conclusion: In areas with a high prevalence of G6PD deficiency that overlap with malaria endemicity, availability and validation of the diagnostic performance of quantitative POC tests are of absolute importance. Carestart™ biosensor and STANDARD G6PD kits showed high reliability and performed well in comparison to the spectrophotometric reference standard.

Genotypic and phenotypic characterization of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Guangzhou, China

BACKGROUND

G6PD deficiency is a common inherited disorder worldwide and has a higher incidence rate in southern China. Many variants of G6PD result from point mutations in the G6PD gene, leading to decreased enzyme activity. This study aimed to analyse the genotypic and phenotypic characteristics of G6PD deficiency in Guangzhou, China.

METHODS

In this study, a total of 20,208 unrelated participants were screened from 2020 to 2022. G6PD deficiency was further analysed by quantitative enzymatic assay and G6PD mutation analysis. The unidentified genotype of the participants was further ascertained by direct DNA sequencing.

RESULTS

A total of 12 G6PD mutations were identified. Canton (c.1376G>T) and Kaiping (c.1388G>A) were the most common variants, and different mutations led to varying levels of G6PD enzyme activity. Comparing the enzyme activities of the 6 missense mutations between the sexes, we found significant differences (P < 0.05) in the enzyme activities of both male hemizygotes and female heterozygotes. Two previously unreported mutations (c.1438A>T and c.946G>A) were identified.

CONCLUSIONS

This study provided detailed genotypes of G6PD deficiency in Guangzhou, which could be valuable for diagnosing and researching G6PD deficiency in this area.

Polyclonality in Sclerosing Angiomatoid Nodular Transformation of the Spleen

Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a morphologically distinctive lesion. Although the clinical course of SANT is benign, its reactive or neoplastic nature remains to be clarified. Furthermore, some investigators have suggested that SANT is related to IgG4 sclerosing lesion or inflammatory pseudotumor with stromal cells positive for Epstein-Barr virus (EBV). In this study, we assessed 22 cases of SANT derived from adult women. Clinical data and follow-up information were obtained by chart review. Immunohistochemical studies for IgG4, IgG, and CD21 stains and in situ hybridization to detect EBV-encoded small RNAs were performed. We also assessed genomic DNA extracted from paraffin-embedded tissue for human androgen-receptor α gene analysis using conventional and methylation-specific polymerase chain reaction methods. The median patient age was 41.5 years (range, 25 to 82 y). Most (77%) patients presented with a single mass that was detected incidentally (59%). The mean size of the lesions was 3.8 cm (range, 1.0 to 9.0 cm). Clinical symptoms correlated with multiple lesions (P=0.043) but not lesional size (P=0.637) or location in the spleen (hilum vs. periphery, P=0.696). None of the cases had evidence of IgG4-related disease or recurred after splenectomy. The mean number of IgG4 cells was 27.7 (range, 4 to 125), and the mean IgG4/IgG ratio was 16.4% (range, 1.6% to 55.7%) with only 2 cases being >40%. Cases with higher IgG4 cells did not correlate with inflammatory pseudotumor-like morphology. No lesions were positive for EBV-encoded small RNAs, and almost all cases with informative results (n=19) showed a polyclonal pattern. We conclude that SANT is a polyclonal, reactive lesion rather than a neoplasm.

Glucose-6-phosphate dehydrogenase deficiency in transfusion medicine: the unknown risks

The hallmark of glucose-6-phosphate dehydrogenase (G6PD) deficiency is red blood cell (RBC) destruction in response to oxidative stress. Patients requiring RBC transfusions may simultaneously receive oxidative medications or have concurrent infections, both of which can induce haemolysis in G6PD-deficient RBCs. Although it is not routine practice to screen healthy blood donors for G6PD deficiency, case reports identified transfusion of G6PD-deficient RBCs as causing haemolysis and other adverse events. In addition, some patient populations may be more at risk for complications associated with transfusions of G6PD-deficient RBCs because they receive RBCs from donors who are more likely to have G6PD deficiency. This review discusses G6PD deficiency, its importance in transfusion medicine, changes in the RBC antioxidant system (of which G6PD is essential) during refrigerated storage and mechanisms of haemolysis. In addition, as yet unanswered questions that could be addressed by translational and clinical studies are identified and discussed.

Skewed X inactivation and survival: a 13-year follow-up study of elderly twins and singletons

In mammalian females, one of the two X chromosomes is inactivated in early embryonic life. Females are therefore mosaics for two cell populations, one with the maternal and one with the paternal X as the active X chromosome. A skewed X inactivation is a marked deviation from a 50:50 ratio. In populations of women past 55-60 years of age, an increased degree of skewing (DS) is found. Here the association between age-related skewing and mortality is analyzed in a 13-year follow-up study of 500 women from three cohorts (73-100 years of age at intake). Women with low DS had significantly higher mortality than the majority of women who had a more skewed DS (hazard ratio: 1.30; 95% CI: 1.04-1.64). The association between X inactivation and mortality was replicated in dizygotic twin pairs for which the co-twin with the lowest DS also had a statistically significant tendency to die first in the twin pairs with the highest intra-pair differences in DS (proportion: 0.71; 95% CI: 0.52-0.86). Both results suggest that lower DS is associated with higher mortality. We therefore propose that age-related skewing may be partly due to a population selection with lower mortality among those with higher DS.