Expanded Clinical Pharmacogenetics Implementation Consortium Guideline for Medication Use in the Context of G6PD Genotype

Fava Bean- Versus Non-Fava Bean-Induced Acute Hemolytic Crisis in Children with Glucose-6-Phosphate Dehydrogenase Deficiency: A Prospective Comparative Study

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a red cell enzymopathy in which exposure to oxidative stressors, such as drugs or fava bean ingestion, can trigger acute hemolytic episodes (AHEs). This study aimed to compare the clinical characteristics of fava bean-induced hemolysis (FBIH) with non-fava bean-induced hemolysis (NFBIH) in children with G6PD deficiency in a high-prevalence setting.

METHODS

A prospective cohort study was conducted at a region referral hospital in Oman. Hospital records of children hospitalized for AHE due to G6PD deficiency over a 3-year period were analyzed. Participants were categorized into FBIH and NFBIH groups based on the documented precipitating factor.

RESULTS

Among the 236 recruited cases, 51.6% AHEs were attributed to FBIH. Children with FIBH were younger, more likely to present with abdominal pain, and had greater severity of hemolysis upon admission (hemoglobin: 4.8 vs. 6.7 g/dL; p < 0.001). Lab markers such as serum ferritin, blood urea, lactate dehydrogenase, and alkaline phosphatase were significantly elevated in FBIH. The least squares regression model demonstrated a strong link between various predictor variables and hemoglobin levels, explaining about 76.6% of the variance in the study cohort.

CONCLUSION

Children with FBIH experience more severe hemolytic episodes compared to those with NFBIH. Our statistical model identified clinical and laboratory parameters potentially useful in early risk stratification during AHEs. Culturally sensitive dietary education of patients and caregivers is necessary, particularly in regions where fava beans are a dietary staple. The potential influence of specific G6PD genotypes within the NFBIH group merits future investigation.

Analytical and operational considerations of measuring glucose 6-phosphate dehydrogenase (G6PD) activity using a fully automated assay

OBJECTIVES

This study determined the performance characteristics of a quantitative glucose-6-phosphate dehydrogenase (G6PD) assay with automated lysis and evaluated the robustness of the operational workflow following implementation in a hospital laboratory.

METHODS

The G6PD activity was measured in whole blood using an enzymatic quantitative test on a Roche cobas c501 analyzer with onboard lysis configuration and normalized to hemoglobin (Hb). The performance characteristics of the method and stability of G6PD in whole blood collected in EDTA-containing tubes were evaluated, and the reference interval was established on a population of healthy individuals (n = 279). The robustness of this automated workflow for sample lysis was evaluated during validation and after implementation for routine clinical use for 18 months and in 2,181 patients.

RESULTS

The G6PD assay was linear from 0.7 to 16.5 U/g Hb. Inter- and intra-assay precision using control and patient samples was below 12%. The G6PD results correlated well with a reference laboratory method (r = 0.96, y = 0.9615x - 1.222). The reference interval in our population was 9.8 to 15.5 U/g Hb. There were no interferences by lipemia and icteria, although grossly hemolyzed specimens may be affected. The testing workflow requires analyzing samples within minutes from mixing and loading into the instrument to avoid sample sedimentation. Measures to repeat samples with Hb 8.0 g/dL or less identified sedimented samples. In our patient population, 10.6% and 5.8% of the total males and females tested were G6PD deficient, respectively.

CONCLUSIONS

The G6PD assay with automated lysis is acceptable for patient testing. Several measures ensured the robustness of this workflow in a hospital laboratory.

The Prevalence of Peripheral Erythrophagocytosis in Pediatric Immune-Mediated Hemolytic Anemia

BACKGROUND

Peripheral erythrophagocytosis appears to be a unique sign of acquired immune-mediated hemolytic anemia. It is said to be rare but its prevalence among patients with autoimmune hemolytic anemia has not been studied.

METHODS

In this retrospective study from July 2014 to June 2024, the clinical and laboratory features, treatment and outcomes of children diagnosed with autoimmune hemolytic anemia were described. The prevalence of peripheral erythrophagocytosis was compared to a group of children with hereditary spherocytosis at the time of first diagnosis seen in the same period.

RESULTS

Twelve consecutive children with autoimmune hemolytic anemia were included. There were four female patients. The mean age was 6.7 (range 0.8 to 16.6) years. The mean hemoglobin was 6.0 (range 2.5 to 8.1) g/dL. Seven patients were positive by a direct antiglobulin test, three were positive with cold agglutinins and two were positive on both tests. In seven cases, an acute infection appeared to be the precipitating factor. Mycoplasma pneumoniae infection was documented in three and suspected in another two cases. Peripheral erythrophagocytosis was present in five cases (42%) but was not found at diagnosis in any of the 16 cases of hereditary spherocytosis (p = 0.0081). Six children had pre-existing diseases, including two with hereditary hemolytic anemia.

CONCLUSIONS

Peripheral erythrophagocytosis is a relatively common and characteristic finding in pediatric autoimmune hemolytic anemia and should be actively looked for in the evaluation of acute hemolysis, including in children with pre-existing hereditary hemolytic disorders.

Pharmacogenetics of the Treatment of Neglected Diseases

BACKGROUND/OBJECTIVES

Pharmacogenetics (PGx) aims to identify individuals more likely to suffer from adverse reactions or therapeutic failure in drug treatments. However, despite most of the evidence in this area being from European populations, some diseases have also been neglected, such as HIV infection, malaria, and tuberculosis. With this review, we aim to emphasize which pharmacogenetic tests are ready to be implemented in treating neglected diseases that have some evidence and call attention to what is missing for these three diseases.

METHODS

A critical literature review on the PGx of HIV infection, malaria, and tuberculosis was performed.

RESULTS

There are three PGx guidelines for antiretroviral drugs used in HIV infection, one for malaria, and none for tuberculosis. Some evidence is already available, and some genes have already been identified, such as CYP2D6 for primaquine treatment and NAT2 for isoniazid. However, some barriers to the implementation are the lack of evidence due to the few studies on the diseases themselves and the admixture of the most affected populations, which must be considered, given the genetic differentiation of these populations.

CONCLUSIONS

PGx tests such as abacavir are already implemented in some places, and efavirenz/atazanavir is ready to implement if this medication is used. Other gene-drug associations were found but still do not present a clear recommendation. We call attention to the need to generate more evidence for testing treatments for other neglected diseases, such as malaria and tuberculosis, given their epidemiological importance and for the public health of less favored populations.

Innovation in cancer pharmacotherapy through integrative consideration of germline and tumor genomes

Precision cancer medicine is widely established, and numerous molecularly targeted drugs for various tumor entities are approved or are in development. Personalized pharmacotherapy in oncology has so far been based primarily on tumor characteristics, for example, somatic mutations. However, the response to drug treatment also depends on pharmacological processes summarized under the term ADME (absorption, distribution, metabolism, and excretion). Variations in ADME genes have been the subject of intensive research for >5 decades, considering individual patients' genetic makeup, referred to as pharmacogenomics (PGx). The combined impact of a patient's tumor and germline genome is only partially understood and often not adequately considered in cancer therapy. This may be attributed, in part, to the lack of methods for combined analysis of both data layers. Optimized personalized cancer therapies should, therefore, aim to integrate molecular information, which derives from both the tumor and the germline genome, and taking into account existing PGx guidelines for drug therapy. Moreover, such strategies should provide the opportunity to consider genetic variants of previously unknown functional significance. Bioinformatic analysis methods and corresponding algorithms for data interpretation need to be developed to integrate PGx data in cancer therapy with a special meaning for interdisciplinary molecular tumor boards, in which cancer patients are discussed to provide evidence-based recommendations for clinical management based on individual tumor profiles. SIGNIFICANCE STATEMENT: The era of personalized oncology has seen the emergence of drugs tailored to genetic variants associated with cancer biology. However, the full potential of targeted therapy remains untapped owing to the predominant focus on acquired tumor-specific alterations. Optimized cancer care must integrate tumor and patient genomes, guided by pharmacogenomic principles. An essential prerequisite for realizing truly personalized drug treatment of cancer patients is the development of bioinformatic tools for comprehensive analysis of all data layers generated in modern precision oncology programs.

Pharmacogenomic profiling of the South Korean population: Insights and implications for personalized medicine

Adverse drug reactions (ADRs) pose substantial public health issues, necessitating population-specific characterization due to variations in pharmacogenes. This study delineates the pharmacogenomic (PGx) landscape of the South Korean (SKR) population, focusing on 21 core pharmacogenes. Whole genome sequencing (WGS) was conducted on 396 individuals, including 99 healthy volunteers, 95 patients with chronic diseases, 81 with colon cancer, 81 with breast cancer, and 40 with gastric cancer, to identify genotype-specific drug dosing recommendations. Our detailed analysis, utilizing high-throughput genotyping (HTG) of CYP2D6 and comparative data from the 1,000 Genomes Project (1 KG) and the US National Marrow Donor Program (NMDP), revealed significant pharmacogenetic diversity in core pharmacogenes such as CYP2B6, CYP2C19, CYP4F2, NUDT15, and CYP2D6. Notably, intermediate metabolizer frequencies for CYP2B6 in SKR (3.28%) were comparable to Europeans (5.77%) and East Asians (5.36%) but significantly differed from other global populations (p < 0.01). For CYP2C19, 48.74% of SKR individuals were classified as intermediate metabolizers, with the *35 allele (2.02%) being unique to SKR, the allele not observed in other East Asian populations. Additionally, the high-risk *3 allele in CYP4F2 was significantly more frequent in SKR (34.72%) than in other East Asian populations (p < 0.01). NUDT15 poor metabolizers were found in 0.76% of SKR, aligning closely with other East Asians (1.59%), while TPMT poor metabolizers were predominantly observed in Europeans and Africans, with one case in SKR. We identified significant allele frequency differences in CYP2D6 variants rs1065852 and rs1135840. Among the 72 drugs analyzed, 93.43% (n = 370) of patients required dosage adjustments for at least one drug, with an average of 4.5 drugs per patient. Moreover, 31.31% (n = 124) required adjustments for more than five drugs. These findings reveal the substantial pharmacogenetic diversity of the SKR population within the global population, emphasizing the urgency of integrating population-specific PGx data into clinical practice to ensure safe and effective drug therapies. This comprehensive PGx profiling in SKR not only advances personalized medicine but also holds the potential to significantly improve healthcare outcomes on a broader scale.

Medications and Acute Hemolysis in G6PD-Deficient Patients - A Real-World Study

Many drug labels contain precautions of use in G6PD-deficient patients due to hemolytic concerns, but much of this is based on scarce clinical, epidemiological, or structural data. In this real-world study, we aimed to examine if the administration of presumably risky medications for G6PD-deficient patients was followed by hemolysis. The study is based on data from Clalit Health Services database that provides inclusive health care for more than half of the Israeli population (~ 4.7 million). Within the database, we identified all G6PD-deficient patients by G6PD <6 U/g Hb. Within the G6PD-deficient cohort, we identified all hospitalizations with a discharge diagnosis of hemolysis (January 1, 2010 to December 31, 2022), validated the cases, and identified the culprit event. For the rest of the G6PD-deficient patients with no-hemolysis, we recorded filled prescriptions of medications listed as presumably risky. We identified 31,962 G6PD-deficient patients. Within the cohort, there were 71 cases of major hemolysis requiring hospitalization (0.2% of the cohort), of whom 51 (71.8%) had been caused by ingestion of fava beans, six (8.5%) were associated with an infection, and three (4.2%) suggested to be associated with medications (nitrofurantoin, phenazopyridine, and a "pain killer"). Within the 31,875 patients with no major hemolysis, nitrofurantoin has been prescribed safely to 1,366 G6PD-deficient males and females; hundreds/thousands of G6PD-deficient patients had been prescribed safely ciprofloxacin, glibenclamide, ofloxacin, phenazopyridine, sulfamethoxazole/cotrimoxazole, sulfasalazine, hydroxychloroquine, glimepiride, mesalazine, and sulfacetamide. In this real-world study, we are showing that a list of medications, suspected previously as carrying risks for hemolysis in G6PD-deficient patients, have been prescribed safely to G6PD-deficient patients, providing reassurance to patients, prescribers, and regulators.

Functional analysis of G6PD variants associated with low G6PD activity in the All of Us Research Program

The glucose-6-phosphate dehydrogenase (G6PD) enzyme protects red blood cells against oxidative damage. Individuals with G6PD-impairing polymorphisms are at risk of hemolytic anemia from oxidative stressors. Prevention of G6PD deficiency-related hemolytic anemia is achievable by identifying affected individuals through G6PD genetic testing. However, accurately predicting the clinical consequence of G6PD variants is limited by over 800 G6PD variants which remain of uncertain significance (VUS). There also remains inconsistency in which deficiency-causing variants are included in genetic testing arrays: many institutions only test c.202G > A, though dozens of other variants can cause G6PD deficiency. Here, we improve G6PD genotype interpretations using the All of Us Research Program data and a yeast functional assay. We confirm that G6PD coding variants are the main contributor to decreased G6PD activity and that 13% of individuals in the All of Us data with deficiency-causing variants would be missed by only genotyping for c.202G > A. We expand clinical interpretation for G6PD VUS, reporting that c.595A > G ("Dagua" or "Açores") and the novel variant c.430C > G reduce activity sufficiently to lead to G6PD deficiency. We also provide evidence that 5 missense VUS are unlikely to lead to G6PD deficiency, and we applied the new World Health Organization (WHO) guidelines to recommend classifying 2 synonymous variants as WHO Class C. In total, we provide new or updated clinical interpretations for 9 G6PD variants. We anticipate these results will improve the accuracy, and prompt increased use, of G6PD genetic tests through a more complete clinical interpretation of G6PD variants.

Pharmacogenetic analysis of structural variation in the 1000 genomes project using whole genome sequences

While significant strides have been made in understanding pharmacogenetics (PGx) and gene-drug interactions, there remains limited characterization of population-level PGx variation. This study aims to comprehensively profile global star alleles (haplotype patterns) and phenotype frequencies in 58 pharmacogenes associated with drug absorption, distribution, metabolism, and excretion. PyPGx, a star-allele calling tool, was employed to identify star alleles within high-coverage whole genome sequencing (WGS) data from the 1000 Genomes Project (N = 2504; 26 global populations). This process involved detecting structural variants (SVs), such as gene deletions, duplications, hybrids, as well as single nucleotide variants and insertion-deletion variants. The majority of our PyPGx calls for star alleles and phenotype frequencies aligned with the Pharmacogenomics Knowledge Base, although notable population-specific frequencies differed at least twofold. Validation efforts confirmed known SVs while uncovering several novel SVs currently undefined as star alleles. Additionally, we identified 210 small nucleotide variants associated with severe functional consequences that are not defined as star alleles. The study serves as a valuable resource, providing updated population-level star allele and phenotype frequencies while incorporating SVs. It also highlights the burgeoning potential of cost-effective WGS for PGx genotyping, offering invaluable insights to improve tailored drug therapies across diverse populations.

Mapping the Pharmacogenetic Landscape in a Ugandan Population: Implications for Personalized Medicine in an Underrepresented Population

Africans are extremely underrepresented in global genomic research. African populations face high burdens of communicable and non-communicable diseases and experience widespread polypharmacy. As population-specific genetic studies are crucial to understanding unique genetic profiles and optimizing treatments to reduce medication-related complications in this diverse population, the present study aims to characterize the pharmacogenomics profile of a rural Ugandan population. We analyzed low-pass whole genome sequencing data from 1998 Ugandans to investigate 18 clinically actionable pharmacogenes in this population. We utilized PyPGx to identify star alleles (haplotype patterns) and compared allele frequencies across populations using the Pharmacogenomics Knowledgebase PharmGKB. Clinical interpretations of the identified alleles were conducted following established dosing guidelines. Over 99% of participants displayed actionable phenotypes across the 18 pharmacogenes, averaging 3.5 actionable genotypes per individual. Several variant alleles known to affect drug metabolism (i.e., CYP3A5*1, CYP2B6*9, CYP3A5*6, CYP2D6*17, CYP2D6*29, and TMPT*3C)-which are generally more prevalent in African individuals-were notably enriched in the Ugandan cohort, beyond reported frequencies in other African peoples. More than half of the cohort exhibited a predicted impaired drug response associated with CFTR, IFNL3, CYP2B6, and CYP2C19, and approximately 31% predicted altered CYP2D6 metabolism. Potentially impaired CYP2C9, SLCO1B1, TPMT, and DPYD metabolic phenotypes were also enriched in Ugandans compared with other African populations. Ugandans exhibit distinct allele profiles that could impact drug efficacy and safety. Our findings have important implications for pharmacogenomics in Uganda, particularly with respect to the treatment of prevalent communicable and non-communicable diseases, and they emphasize the potential of pharmacogenomics-guided therapies to optimize healthcare outcomes and precision medicine in Uganda.

Patterns of pharmacogenetic variation in nine biogeographic groups

Frequencies of pharmacogenetic (PGx) variants are known to differ substantially across populations but much of the available PGx literature focuses on one or a few population groups, often defined in nonstandardized ways, or on a specific gene or variant. Guidelines produced by the Clinical Pharmacogenetic Implementation Consortium (CPIC) provide consistent methods of literature extraction, curation, and reporting, including comprehensive curation of allele frequency data across nine defined "biogeographic groups" from the PGx literature. We extracted data from 23 CPIC guidelines encompassing 19 genes to compare the sizes of the populations from each group and allele frequencies of altered function alleles across groups. The European group was the largest in the curated literature for 16 of the 19 genes, while the American and Oceanian groups were the smallest. Nearly 200 alleles were detected in nonreference groups that were not reported in the largest (reference) group. The genes CYP2B6 and CYP2C9 were more likely to have higher frequencies of altered function alleles in nonreference groups compared to the reference group, while the genes CYP4F2, DPYD, SLCO1B1, and UGT1A1 were less likely to have higher frequencies in nonreference groups. PGx allele frequencies and function differ substantially across nine biogeographic groups, all but two of which are underrepresented in available PGx data. Awareness of these differences and increased efforts to characterize the breadth of global PGx variation are needed to ensure that implementation of PGx-guided drug selection does not further widen existing health disparities among populations currently underrepresented in PGx data.

Sulfamethoxazole-Trimethoprim Prophylaxis in Pediatric Oncology Patients With Glucose-6-Phosphate Dehydrogenase Deficiency

We sought to determine whether Pneumocystis jirovecii pneumonia prophylaxis with sulfamethoxazole-trimethoprim (SMX-TMP) is associated with an increased frequency of acute hemolytic anemia in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency versus non-G6PD-deficient controls in a pediatric oncology population. There was no statistically significant difference in change in hemoglobin or transfusion requirements after starting SMX-TMP between groups. These findings suggest no increased risk of acute hemolytic anemia with SMX-TMP administered at prophylaxis doses in patients with G6PD deficiency.

Functional Analysis of G6PD Variants Associated With Low G6PD Activity in the All of Us Research Program

Glucose-6-phosphate dehydrogenase (G6PD) protects red blood cells against oxidative damage through regeneration of NADPH. Individuals with G6PD polymorphisms (variants) that produce an impaired G6PD enzyme are usually asymptomatic, but at risk of hemolytic anemia from oxidative stressors, including certain drugs and foods. Prevention of G6PD deficiency-related hemolytic anemia is achievable through G6PD genetic testing or whole-genome sequencing (WGS) to identify affected individuals who should avoid hemolytic triggers. However, accurately predicting the clinical consequence of G6PD variants is limited by over 800 G6PD variants which remain of uncertain significance. There also remains significant variability in which deficiency-causing variants are included in pharmacogenomic testing arrays across institutions: many panels only include c.202G>A, even though dozens of other variants can also cause G6PD deficiency. Here, we seek to improve G6PD genotype interpretation using data available in the All of Us Research Program and using a yeast functional assay. We confirm that G6PD coding variants are the main contributor to decreased G6PD activity, and that 13% of individuals in the All of Us data with deficiency-causing variants would be missed if only the c.202G>A variant were tested for. We expand clinical interpretation for G6PD variants of uncertain significance; reporting that c.595A>G, known as G6PD Dagua or G6PD Açores, and the newly identified variant c.430C>G, reduce activity sufficiently to lead to G6PD deficiency. We also provide evidence that five missense variants of uncertain significance are unlikely to lead to G6PD deficiency, since they were seen in hemi- or homozygous individuals without a reduction in G6PD activity. We also applied the new WHO guidelines and were able to classify two synonymous variants as WHO class C. We anticipate these results will improve the accuracy, and prompt increased use, of G6PD genetic tests through a more complete clinical interpretation of G6PD variants. As the All of Us data increases from 245,000 to 1 million participants, and additional functional assays are carried out, we expect this research to serve as a template to enable complete characterization of G6PD deficiency genotypes. With an increased number of interpreted variants, genetic testing of G6PD will be more informative for preemptively identifying individuals at risk for drug- or food-induced hemolytic anemia.

The Case for Pre-Emptive Pharmacogenetic Screening in South Africa

Lack of equitable representation of global genetic diversity has hampered the implementation of genomic medicine in under-represented populations, including those on the African continent. Data from the multi-national Pre-emptive Pharmacogenomic Testing for Preventing Adverse Drug Reactions (PREPARE) study suggest that genotype guidance for prescriptions reduced the incidence of clinically relevant adverse drug reactions (ADRs) by 30%. In this study, hospital dispensary trends from a tertiary South African (SA) hospital (Steve Biko Academic Hospital; SBAH) were compared with the drugs monitored in the PREPARE study. Dispensary data on 29 drugs from the PREPARE study accounted for ~10% of total prescriptions and ~9% of the total expenditure at SBAH. VigiLyze data from the South African Health Products Regulatory Authority were interrogated for local ADRs related to these drugs; 27 were listed as being suspected, concomitant, or interacting in ADR reports. Furthermore, a comparison of pharmacogene allele frequencies between African and European populations was used to frame the potential impact of pre-emptive pharmacogenetic screening in SA. Enumerating the benefit of pre-emptive pharmacogenetic screening in SA will only be possible once we initiate its full application. However, regional genomic diversity, disease burden, and first-line treatment options could be harnessed to target stratified PGx today.

Frequencies of pharmacogenomic alleles across biogeographic groups in a large-scale biobank

Pharmacogenomics (PGx) is an integral part of precision medicine and contributes to the maximization of drug efficacy and reduction of adverse drug event risk. Accurate information on PGx allele frequencies improves the implementation of PGx. Nonetheless, curating such information from published allele data is time and resource intensive. The limited number of allelic variants in most studies leads to an underestimation of certain alleles. We applied the Pharmacogenomics Clinical Annotation Tool (PharmCAT) on an integrated 200K UK Biobank genetic dataset (N = 200,044). Based on PharmCAT results, we estimated PGx frequencies (alleles, diplotypes, phenotypes, and activity scores) for 17 pharmacogenes in five biogeographic groups: European, Central/South Asian, East Asian, Afro-Caribbean, and Sub-Saharan African. PGx frequencies were distinct for each biogeographic group. Even biogeographic groups with similar proportions of phenotypes were driven by different sets of dominant PGx alleles. PharmCAT also identified "no-function" alleles that were rare or seldom tested in certain groups by previous studies, e.g., SLCO1B1∗31 in the Afro-Caribbean (3.0%) and Sub-Saharan African (3.9%) groups. Estimated PGx frequencies are disseminated via the PharmGKB (The Pharmacogenomics Knowledgebase: www.pharmgkb.org). We demonstrate that genetic biobanks such as the UK Biobank are a robust resource for estimating PGx frequencies. Improving our understanding of PGx allele and phenotype frequencies provides guidance for future PGx studies and clinical genetic test panel design, and better serves individuals from wider biogeographic backgrounds.

Implementation of Pharmacogenetics in First-Line Care: Evaluation of Its Use by General Practitioners

Pharmacogenetics (PGx) can explain/predict drug therapy outcomes. There is, however, unclarity about the use and usefulness of PGx in primary care. In this study, we investigated PGx tests ordered by general practitioners (GPs) in 2021 at Dept. Clinical Chemistry, Erasmus MC, and analyzed the gene tests ordered, drugs/drug groups, reasons for testing and single-gene versus panel testing. Additionally, a survey was sent to 90 GPs asking about their experiences and barriers to implementing PGx. In total, 1206 patients and 6300 PGx tests were requested by GPs. CYP2C19 was requested most frequently (17%), and clopidogrel was the most commonly indicated drug (23%). Regarding drug groups, antidepressants (51%) were the main driver for requesting PGx, followed by antihypertensives (26%). Side effects (79%) and non-response (27%) were the main indicators. Panel testing was preferred over single-gene testing. The survey revealed knowledge on when and how to use PGx as one of the main barriers. In conclusion, PGx is currently used by GPs in clinical practice in the Netherlands. Side effects are the main reason for testing, which mostly involves antidepressants. Lack of knowledge is indicated as a major barrier, indicating the need for more education on PGx for GPs.

Children's Oncology Group's 2023 blueprint for research: Pharmacy

Children's Oncology Group (COG) pharmacists and pharmacy technicians from more than 200 COG-member institutions comprise the COG Pharmacy Discipline. Discipline members serve an essential role in the design and execution of COG clinical trials. Core activities include study drug management, study drug access, clinical trial operations, protocol harmonization, and direct patient care. Discipline members are also actively involved in continuing education, membership engagement, and research across other COG committees/domains. Future areas of committed growth for the discipline include pharmacogenomics, pharmacokinetics, pharmacoeconomics, pharmaceutics, and implementation science.

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.

Risk of Hemolytic Anemia in IBD Patients with Glucose-6-Phosphate Dehydrogenase Deficiency Treated with Mesalamine: Results of a Retrospective-Prospective and Ex Vivo Study

BACKGROUND

Mesalamine is one of the most-used drugs in inflammatory bowel disease (IBD), especially ulcerative colitis. Regulatory agencies have listed mesalamine as an unsafe drug in subjects with glucose-6-phosphate dehydrogenase (G6PD) deficiency based on the risk of hemolysis, although scientific evidence is lacking. The occurrence of acute and/or chronic hemolytic anemia in IBD patients with G6PD deficiency exposed to mesalamine was evaluated.

METHODS

In this multicenter study, IBD patients with G6PD deficiency (cases) receiving mesalamine were retrospectively evaluated for acute, and prospectively for chronic, hemolysis. The presence of hemolytic anemia was based on red blood cell and reticulocyte count, hemoglobin, lactate dehydrogenase, unconjugated bilirubin, and haptoglobin levels. Cases were compared with controls (IBD patients with normal G6PD).

RESULTS

A total of 453 IBD patients (mean age 52.1 ± 16.0 years; 58.5% female) were enrolled. Ulcerative colitis was present in 75% of patients. G6PD deficiency was detected in 17% of patients. Oral mesalamine was used in 67.9% of ulcerative colitis and in 32.4% of Crohn's disease cases. None of the 78 IBD patients with G6PD deficiency receiving mesalamine underwent hospitalization or specific treatment for acute hemolytic anemia. Relevant differences in chronic hemolysis markers were not observed in 30 cases compared with 112 controls receiving mesalamine (≤4500 mg/day). Marker modifications were also observed in mesalamine-free cases, consistent with the basal rate of erythrophagocytosis in G6PD deficiency. Ex vivo experiments showed the release of methemoglobin by G6PD deficient RBCs upon mesalamine challenge, only above 2.5 mg/mL, a concentration never reached in the clinical setting.

CONCLUSIONS

This study provides, for the first time, evidence that mesalamine is safe in G6PD deficiency at a dosage of up to 4500 mg/day.

Utilization of Glucose-6-Phosphate Dehydrogenase Test and the Prevalence of Enzyme Deficiency in Korea

Glucose-5-phosphate dehydrogenase (G6PD) deficiency is an X-linked genetic disorder that affects red blood cells' metabolism. This retrospective study aimed to investigate the prevalence and characteristics of G6PD testing in Korea. Data were collected from laboratory information systems between July 2021 and June 2022. A total of 5193 patients (1722 males and 3471 females) with a median age of 55.1 years (interquartile range, IQR 44.6 to 64.5) were tested for whole blood G6PD, with 1.6% of tests performed on patients of non-Korean ethnicity. The majority of tests were performed in hospitals (37.7%) or local clinics (34.5%). Interestingly, no female children were tested for whole blood G6PD during the study period. The prevalence of decreased G6PD activity (<7.9 U/g Hb) was 0.4% (19/5111 Koreans and 2/82 non-Koreans), and only seven male patients with G6PD deficiency (<30% of the male median) were identified, with ages ranging from 4.8 months to 50.2 years. No female patients with G6PD deficiency were found. Further research is necessary to determine the clinical significance of G6PD test results and monitor their use.

Functional interpretation, cataloging, and analysis of 1,341 glucose-6-phosphate dehydrogenase variants

Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects over 500 million individuals who can experience anemia in response to oxidative stressors such as certain foods and drugs. Recently, the World Health Organization (WHO) called for revisiting G6PD variant classification as a priority to implement genetic medicine in low- and middle-income countries. Toward this goal, we sought to collect reports of G6PD variants and provide interpretations. We identified 1,341 G6PD variants in population and clinical databases. Using the ACMG standards and guidelines for the interpretation of sequence variants, we provided interpretations for 268 variants, including 186 variants that were not reported or of uncertain significance in ClinVar, bringing the total number of variants with non-conflicting interpretations to 400. For 414 variants with functional or clinical data, we analyzed associations between activity, stability, and current classification systems, including the new 2022 WHO classification. We corroborated known challenges with classification systems, including phenotypic variation, emphasizing the importance of comparing variant effects across individuals and studies. Biobank data made available by All of Us illustrate the benefit of large-scale sequencing and phenotyping by adding additional support connecting variants to G6PD-deficient anemia. By leveraging available data and interpretation guidelines, we created a repository for information on G6PD variants and nearly doubled the number of variants with clinical interpretations. These tools enable better interpretation of G6PD variants for the implementation of genetic medicine.

The Implementation of Pharmacogenetics in the United Kingdom

There is considerable inter-individual variability in the effectiveness and safety of pharmaceutical interventions. This phenomenon can be attributed to a multitude of factors; however, it is widely acknowledged that common genetic variation affecting drug absorption or metabolism play a substantial contributory role. This is a concept known as pharmacogenetics. Understanding how common genetic variants influence responses to medications, and using this knowledge to inform prescribing practice, could yield significant advantages for both patients and healthcare systems. Some health services around the world have introduced pharmacogenetics into routine practice, whereas others are less advanced along the implementation pathway. This chapter introduces the field of pharmacogenetics, the existing body of evidence, and discusses barriers to implementation. The chapter will specifically focus on efforts to introduce pharmacogenetics in the NHS, highlighting key challenges related to scale, informatics, and education.