Genetic factors influencing hemoglobin levels in 15,567 blood donors: results from the Danish Blood Donor Study

The influence of demographic and lifestyle factors on blood donation delay among student population: a retrospective study

Objective

This study analysed blood donation deferral trends, reasons and demographic/lifestyle characteristics among students in Huzhou City. The aim was to understand the health status of students and reduce the deferral rate.

Methods

Data on blood donation deferral among students in Huzhou City from 2018 to 2022 were collected and analysed. Deferral trends and main reasons were investigated. Using demographic and lifestyle data from 2,619 cases in 2022, a risk prediction model for deferral was constructed.

Results

The deferral rate among students in Huzhou City from 2018 to 2022 was 12.60% (p = 0.000, 95%CI: 12.14-13.06%), showing a significant increasing trend. Temporary deferral was the main reason, with alanine aminotransferase (ALT), blood pressure (BP) and haemoglobin (Hb) as the main deferral factors. ALT had a deferral rate of 5.23% (4.92-5.53%), BP 3.30% (3.06-3.55%), and Hb 2.92% (2.68-3.15%). Demographic and lifestyle characteristics in 2022 showed no significant differences between education level, household registration and deferral rate (p > 0.05). However, age, sex, blood donation history, sleep quality, diet and mental state had variable effects on ALT, BP, and Hb deferrals (p < 0.05). Logistic regression showed that sex, blood donation history, sleep quality, diet and mental status were independent risk factors for ALT deferral (p < 0.05), with odds ratios (ORs) of 5.057, 2.735, 1.594, 3.679, and 1.957, respectively. Age, blood donation history, sleep quality and mental state were independent risk factors for BP deferral (p < 0.05), with ORs of 0.256, 3.658, 6.042, and 1.812, respectively. Gender, blood donation history and diet were independent risk factors for Hb deferral (p < 0.05), with ORs of 0.244, 0.542, and 3.103, respectively.

Conclusion

Students' health problems require attention. Effective health education should improve self-health management and pre-donation health behaviour to encourage regular blood donation.

Iron status of blood donors

PURPOSE OF REVIEW

This review examines recent research on the prevalence and importance of iron deficiency in blood donors, and on efforts to mitigate it.

RECENT FINDINGS

Premenopausal females, teenagers, and high-frequency donors are at the highest risk for donation-induced iron deficiency, in both high-resource and low-resource settings. The physiology relating iron stores to hemoglobin levels and low hemoglobin deferral is well elucidated in blood donor populations, yet the clinical effects attributable to iron loss in the absence of anemia are challenging to identify. Expanded adoption of ferritin testing is improving donor management but may cause decreases in the blood supply from temporary donor loss. The potential for personalized donor management is emerging with development of computational models that predict individual interdonation intervals that aim to optimize blood collected from each donor while minimizing low hemoglobin deferrals.

SUMMARY

Measures to reduce iron deficiency are available that can be deployed on a standardized or, increasingly, personalized basis. Blood centers, regulators, and donors should continue to evaluate different tactics for addressing this problem, to obtain a balanced approach that is optimal for maintaining adequate collections while safeguarding donor health.

Genetic common variants associated with cerebellar volume and their overlap with mental disorders: a study on 33,265 individuals from the UK-Biobank

Interest in the cerebellum is expanding given evidence of its contributions to cognition and emotion, and dysfunction in various psychopathologies. However, research into its genetic architecture and shared influences with liability for mental disorders is lacking. We conducted a genome-wide association study (GWAS) of total cerebellar volume and underlying cerebellar lobe volumes in 33,265 UK-Biobank participants. Total cerebellar volume was heritable (h2SNP = 50.6%), showing moderate genetic homogeneity across lobes (h2SNP from 35.4% to 57.1%; mean genetic correlation between lobes rg ≈ 0.44). We identified 33 GWAS signals associated with total cerebellar volume, of which 6 are known to alter protein-coding gene structure, while a further five mapped to genomic regions known to alter cerebellar tissue gene expression. Use of summary data-based Mendelian randomisation further prioritised genes whose change in expression appears to mediate the SNP-trait association. In total, we highlight 21 unique genes of greatest interest for follow-up analyses. Using LD-regression, we report significant genetic correlations between total cerebellar volume and brainstem, pallidum and thalamus volumes. While the same approach did not result in significant correlations with psychiatric phenotypes, we report enrichment of schizophrenia, bipolar disorder and autism spectrum disorder associated signals within total cerebellar GWAS results via conditional and conjunctional-FDR analysis. Via these methods and GWAS catalogue, we identify which of our cerebellar genomic regions also associate with psychiatric traits. Our results provide important insights into the common allele architecture of cerebellar volume and its overlap with other brain volumes and psychiatric phenotypes.

Characteristics and causes of pre-donation deferrals at a Chinese blood center

OBJECTIVES

The purpose of this retrospective analysis was to understand the causes and characteristics of the pre-donation deferral, so as to enhance blood safety and improve donor satisfaction.

BACKGROUND

Blood transfusion is crucial in managing a variety of different medical and surgical needs. Its benefits are manifold but there are risks for the recipients. Thus some blood donors are deferred from donating when they do not meet certain criteria. An in-depth understanding of the underlying causes of donor deferral will not only improve donor selection but also ensure blood safety and avoid donor complaints.

MATERIALS AND METHODS

This single-center experience was carried out from 26th July 2018 to 25th July 2019 on all whole blood donors in Tianjin, China. Donors' demographics and information were retrieved; comparisons between deferral data were summarized by the Chi-square test using Statistical Product and Service Solutions (SPSS) application version 22. The difference between groups were considered statistically significant when p < 0.05.

RESULTS

A total of 190,846 participants were included; whereby 119,951 (62.85 %) of participants were first-time blood donors. The pre-donation deferral rate was 9.26 %, and deferral was more likely seen in first-time donors, male donors, and donors of age above 35 years (p < 0.05). Overall, raised alanine aminotransferase (ALT) contributed to 48.46 % of all temporary deferrals, followed by lipaemia (20.71 %). For female donors, low hemoglobin was the leading cause of temporary deferral. Positive hepatitis B surface antigen (Hepatitis B) and syphilis were the two common causes of permanent deferrals, with incidence at 11.65 % and 3.93 %, respectively.

CONCLUSION

Pre-donation deferral remains a significant problem in China and accounted for 9.26 % of participants in this study. Raised ALT and lipaemia were common temporary deferrals, especially among first-time donors, males, and older donors. Appropriate interventions should be taken to address the blood quality, improve the donor retention strategies in order to secure an adequate and safe blood supply.

The impact of blood donation on blood counts and ferritin levels: A multi-center study from the Eastern Mediterranean region

Regular donation of whole blood may lead to iron deficiency. In this study, we aimed to assess the impact of frequent whole blood donation on hematological parameters. Whole blood donors were enrolled from four blood banks located in Saudi Arabia, United Arab Emirates (UAE), Libya and Oman, between 2016 and 2017. SPSS version 21.0 was used to generate descriptive and inferential statistics. A total number of 3096 blood donors were screened (males 93.8 %, females; 6.2 %), with a mean donor age of 35.29 ± 9.31 years. For male blood donors, the majority (1073) had 1-3 previous donations. Increased frequency of donations was significantly associated with increases in age and weight, decreases in Hemoglobin (Hb) and ferritin measures, and increases in Red Blood Cells (RBC) counts. A General Linear Model (GLM) adjusted for age and weight indicated negative impacts on White Blood Cells (WBC) counts and ferritin. A weak correlation between the Hb and ferritin levels was observed (r = 0.160, P > 0.001). For female donors, the majority (63 out of 114) were first time donors. Increased frequency of donations was significantly associated with an increase in age and a decrease in HCT readings. A GLM adjusted for age and weight indicated a negative impact on ferritin. A strong correlation was observed between the Hb and ferritin levels for the most frequent female donors (r = 0.636, P > 0.001). In conclusion, regular whole blood donation impacts hematological parameters in particular the levels of ferritin in the serum.

Genetic determinants of ferritin, haemoglobin levels and haemoglobin trajectories: results from Donor InSight

BACKGROUND AND OBJECTIVES

Blood donors might develop iron deficiency as approximately 250 mg of iron is lost with every donation. Susceptibility to iron deficiency and low haemoglobin levels differs between individuals, which might be due to genetic variation. Therefore, the aim of this study was to investigate associations between single nucleotide polymorphisms (SNPs) and haemoglobin trajectories, haemoglobin levels and ferritin levels in blood donors.

MATERIALS AND METHODS

In 2655 donors participating in the observational cohort study Donor InSight-III (2015-2017), haemoglobin and ferritin levels were measured in venous EDTA whole blood and plasma samples, respectively. Haemoglobin trajectories (stable/declining) were determined by fitting growth-mixture models on repeated pre-donation capillary haemoglobin measurements. Genotyping was done using the UK Biobank - version 2 Axiom Array. Single SNP analyses adopting an additive genetic model on imputed genetic variants were performed for haemoglobin trajectories, haemoglobin levels and ferritin levels. Conditional analyses identified independent SNPs.

RESULTS

Twelve, twenty and twenty-four independent SNPs were associated with haemoglobin trajectories, haemoglobin levels and ferritin levels respectively (P < 1 x 10^-5 ). Rs112016443 reached genome-wide significance for ferritin levels, which influences WDSUB1 expression.

CONCLUSION

Rs112016443 was genome-wide significantly associated with ferritin levels in Dutch donors. Further validation studies are needed, as well as studies towards underlying mechanisms and predicting iron deficiency using SNPs.

Molecular analysis of homeostatic iron regulator, transmembrane protease serine-6, and BTB domain-containing protein-9 variants and iron parameters in blood donors

Genetic variants associated with iron homeostasis have been identified, but their association with iron-related indices and variables among different ethnic populations remains controversial. We aimed to explore the genotype frequency and allelic distribution of three iron-metabolism related variants in homeostatic iron regulator gene (HFE; rs1800562 G/A), transmembrane protease, Serine-6 gene (TMPRSS6; rs855791 A/G), and BTB domain-containing protein-9 gene (BTBD9; rs9357271 C/T) among a sample of the Middle Eastern blood donors and to detect the association of these variants on blood indices, and serum hepcidin/ferritin levels. Real-Time TaqMan genotyping assay for the specified variants was applied for 197 unrelated blood donors. Complete blood picture and serum hepcidin/ferritin levels were assessed. All participants were carriers of rs1800562*G/G genotype for HFE. The frequency of A/A and A/G genotypes of TMPRSS6 rs855791 variant was 55% and 45%, and for C/C, C/T, and T/T of BTBD9 rs9357271, were 15%, 43%, and 42%, respectively. Minor allele frequencies of rs855791*G and rs9357271*C were 0.23 and 0.37. The GGC genotype combination (for HFE/TMPRSS6/BTBD9, respectively) was more frequent in male participants. Higher serum hepcidin and hepcidin/ferritin ratio were observed in TMPRSS6 (A/G) carriers. While subjects with BTBD9 C/T and TT genotypes had lower serum ferritin values and higher levels of hepcidin and hepcidin/ferritin ratio compared with C/C genotype. No significant associations were found with any other blood parameters. In conclusion, TMPRSS6 rs855791 (A/G) and BTBD9 rs9357271 (C/T) variants were prevalent in the present blood donor population and may influence the serum hepcidin and/or ferritin levels.

The Proteomics Study of Compounded HFE/TF/TfR2/HJV Genetic Variations in a Thai Family with Iron Overload, Chronic Anemia, and Motor Neuron Disorder

The mutation of the homeostatic iron regulatory genes (HFE) impaired the hepatic hepcidin transcription leading to the chronic excess of the iron pool, with the adverse consequences of free radical oxidative damages. We herein reported the findings of Thai family members who had the compound of uncommon HFE rs2794719, together with transferrin (TF) rs1867504, transferrin receptor 2 (TfR2) rs7385804, and hemojuvelin (HJV) rs16827043 genetic variants involved in the hepcidin transcriptional pathway. These compounded genetic variants could produce the spectrum of clinical phenotypes that spanned from mild to moderate symptoms of chronic anemia to an established motor neuron disorder. The feasible pathophysiologies were the impairment of the transferrin receptor functions, which affected the endocytic uptake of halo-transferrin into the erythroblast precursors. Such a defect left the erythropoiesis depleted of their iron supply. These alterations also promoted the TfR-independent uptake of iron into other target tissues and left the TrF2/BMP-dependent-hepcidin activation pathway unattended. We used the predicted molecular interactive proteomes to support our speculated dysregulated iron metabolism. During the early stage of an elevated ferritin level, there was no inhibition of ferroportin activities from hepcidin. These pathophysiological processes went on to the point of an iron overload threshold. After that, the hepcidin transcription started to kick in with the resulting decreased serum iron levels and deterioration of clinical symptoms.

Genetic and behavioral modification of hemoglobin and iron status among first-time and high-intensity blood donors

BACKGROUND

Some people rapidly develop iron deficiency anemia following blood donation, while others can repeatedly donate without becoming anemic.

METHODS

Two cohorts of blood donors were studied. Participants (775) selected from a 2-year longitudinal study were classified into six analysis groups based on sex, donation intensity, and low hemoglobin deferral. Associations with iron supplement use, cigarette smoking, and four genetic variants of iron metabolism were examined at enrollment and with longitudinal regression models. An unbiased assessment of genetic variability and ability to repeatedly donate blood without experiencing low hemoglobin deferral was conducted on participants (13,403) in a cross-sectional study who were examined by genome wide association (GWA).

RESULTS

Behaviors and genetic variants were associated with differences in hemoglobin and ferritin change following repeated donation. At least weekly iron supplement use was associated with improved status in first-time donors, while daily use was associated with improved status in high-intensity donors. Cigarette smoking was associated with 0.5 g/dL increased hemoglobin in high-intensity donors. A736V in TMPRSS6 was associated with a rapid drop in hemoglobin and ferritin in first-time females following repeated donation. Conversely, the protective TMPRSS6 genotype was not enriched among high-intensity donors. H63D in HFE was associated with increased hemoglobin in female high-intensity donors. However, no differences in genotype between first-time and high-intensity donors were found in GWA analyses.

CONCLUSION

Behavioral and genetic modifiers contributed to first-time donor hemoglobin and iron status, while iron supplement use was more important than underlying genetics in high-intensity donors.

Impact of risk-dependent interventions on low haemoglobin deferral rates in whole blood donors

BACKGROUND

Blood donors with a relatively low haemoglobin (Hb) level at their previous donation attempt have an increased risk of Hb deferral at the subsequent donation attempt. The aim of this study was to investigate whether the interventions prolongation of donation interval and/or a dietary advice decrease the Hb deferral rate.

METHODS

11 897 whole blood donors with Hb levels from below to 0·2 mmol/l above the cut-off level for donation received either no intervention, a prolongation of the donation interval to six or twelve months, a dietary advice, or both. Deferral rates for low Hb levels at the subsequent donation attempt were compared in the different intervention groups. Additionally, the effects of the interventions on Hb deferral risk and donor return for a subsequent donation attempt were analysed using generalized estimating equations.

RESULTS

The Hb deferral rate was substantially lower in the group that received a prolongation of the donation interval to six months than in the Control Group (12·9% vs. 6·3% in men and 20·4% vs. 13·4% in women). However, the additional benefit of twelve over 6-month interval prolongation was small, and no benefit of a dietary advice showed up. On the other hand, receiving a dietary advice increased the likelihood of donor return for a subsequent donation attempt.

CONCLUSION

Implementation of a protocol for the prolongation of donation intervals to six months for donors with Hb levels from below to slightly above the cut-off level for donation may reduce the deferral rate for low Hb levels while keeping donor lapse at a minimum.

Donor Deferral Due to Low Hemoglobin-An Updated Systematic Review

Blood donors attending a donation session may be deferred from donating blood due to a failure to meet low hemoglobin (Hb) thresholds. This costs the blood donor service and donors valuable time and resources. In addition, donors who are deferred may have more symptoms, and as a direct and/or indirect effect of their experience, return rates of donors deferred for low Hb are reduced, even in repeat donors. It is therefore vital that low Hb deferral (LHD) is minimized. The aim of this updated systematic review is to expand the evidence base for factors which affect a donor's risk of deferral due to low Hb. Studies were identified by searching MEDLINE, Embase, The Cochrane Library, and the WHO International Clinical Trials Registry to March 2019. Demographic data, donor history, hematological/biological factors, and the primary outcome of deferral due to low Hb were extracted. Our primary outcome was deferral due to low Hb. Analyses were descriptive and quantitative; pooled odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by meta-analysis using random-effects models. A total of 116 studies met the inclusion criteria. Meta-analysis showed a significantly greater risk of LHD in females compared with males in studies applying universal Hb thresholds for males and females (OR 14.62 95% CI 12.43-17.19) and in those which used sex-specific thresholds (OR 5.73, 95% CI 4.36-7.53). Higher rates of LHD were also associated with increasing age in men, low body weight, shorter interdonation interval, donors of Hispanic or African descent, higher ambient temperature, donors with low ferritin levels, and donation in a fixed donor center. There was conflicting evidence on the effect of new and repeat donor status, and blood group. This work has strengthened the evidence of the previous review in identifying factors that should be considered in studies of donor deferral and highlighting areas in need of further study, including ABO and Rh blood groups, previous platelet donation, diet, smoking, time of day, and genetic data. These factors may lead to individually tailored donation criteria for safe and efficient donation in the future.

Hepcidin and Anemia: A Tight Relationship

Hepcidin, the master regulator of systemic iron homeostasis, tightly influences erythrocyte production. High hepcidin levels block intestinal iron absorption and macrophage iron recycling, causing iron restricted erythropoiesis and anemia. Low hepcidin levels favor bone marrow iron supply for hemoglobin synthesis and red blood cells production. Expanded erythropoiesis, as after hemorrhage or erythropoietin treatment, blocks hepcidin through an acute reduction of transferrin saturation and the release of the erythroblast hormone and hepcidin inhibitor erythroferrone. Quantitatively reduced erythropoiesis, limiting iron consumption, increases transferrin saturation and stimulates hepcidin transcription. Deregulation of hepcidin synthesis is associated with anemia in three conditions: iron refractory iron deficiency anemia (IRIDA), the common anemia of acute and chronic inflammatory disorders, and the extremely rare hepcidin-producing adenomas that may develop in the liver of children with an inborn error of glucose metabolism. Inappropriately high levels of hepcidin cause iron-restricted or even iron-deficient erythropoiesis in all these conditions. Patients with IRIDA or anemia of inflammation do not respond to oral iron supplementation and show a delayed or partial response to intravenous iron. In hepcidin-producing adenomas, anemia is reverted by surgery. Other hepcidin-related anemias are the “iron loading anemias” characterized by ineffective erythropoiesis and hepcidin suppression. This group of anemias includes thalassemia syndromes, congenital dyserythropoietic anemias, congenital sideroblastic anemias, and some forms of hemolytic anemias as pyruvate kinase deficiency. The paradigm is non-transfusion-dependent thalassemia where the release of erythroferrone from the expanded pool of immature erythroid cells results in hepcidin suppression and secondary iron overload that in turn worsens ineffective erythropoiesis and anemia. In thalassemia murine models, approaches that induce iron restriction ameliorate both anemia and the iron phenotype. Manipulations of hepcidin might benefit all the above-described anemias. Compounds that antagonize hepcidin or its effect may be useful in inflammation and IRIDA, while hepcidin agonists may improve ineffective erythropoiesis. Correcting ineffective erythropoiesis in animal models ameliorates not only anemia but also iron homeostasis by reducing hepcidin inhibition. Some targeted approaches are now in clinical trials: hopefully they will result in novel treatments for a variety of anemias.

Effect of donor, component, and recipient characteristics on hemoglobin increments following red blood cell transfusion

Significant research has focused individually on blood donors, product preparation and storage, and optimal transfusion practice. To better understand the interplay between these factors on measures of red blood cell (RBC) transfusion efficacy, we conducted a linked analysis of blood donor and component data with patients who received single-unit RBC transfusions between 2008 and 2016. Hemoglobin levels before and after RBC transfusions and at 24- and 48-hour intervals after transfusion were analyzed. Generalized estimating equation linear regression models were fit to examine hemoglobin increments after RBC transfusion adjusting for donor and recipient demographic characteristics, collection method, additive solution, gamma irradiation, and storage duration. We linked data on 23 194 transfusion recipients who received one or more single-unit RBC transfusions (n = 38 019 units) to donor demographic and component characteristics. Donor and recipient sex, Rh-D status, collection method, gamma irradiation, recipient age and body mass index, and pretransfusion hemoglobin levels were significant predictors of hemoglobin increments in univariate and multivariable analyses (P < .01). For hemoglobin increments 24 hours after transfusion, the coefficient of determination for the generalized estimating equation models was 0.25, with an estimated correlation between actual and predicted values of 0.5. Collectively, blood donor demographic characteristics, collection and processing methods, and recipient characteristics accounted for significant variation in hemoglobin increments related to RBC transfusion. Multivariable modeling allows the prediction of changes in hemoglobin using donor-, component-, and patient-level characteristics. Accounting for these factors will be critical for future analyses of donor and component factors, including genetic polymorphisms, on posttransfusion increments and other patient outcomes.