A genome-wide meta-analysis yields 46 new loci associating with biomarkers of iron homeostasis.

Iron is essential for many biological functions and iron deficiency and overload have major health implications. We performed a meta-analysis of three genome-wide association studies from Iceland, the UK and Denmark of blood levels of ferritin (N = 246,139), total iron binding capacity (N = 135,430), iron (N = 163,511) and transferrin saturation (N = 131,471). We found 62 independent sequence variants associating with iron homeostasis parameters at 56 loci, including 46 novel loci.

Serum ferritin level is inversely related to number of previous pregnancy losses in women with recurrent pregnancy loss.

Objective: To study whether low serum ferritin (s-ferritin) levels are associated with recurrent pregnancy loss (RPL), and whether low s-ferritin predicts the risk of another pregnancy loss or the ability to conceive.

Design: Cohort study.

Setting: Fertility clinic at a university hospital.

The donors perceived positive and negative effects of blood donation.

Background: Occasionally blood donation has a negative influence on some donors, while others express feelings of increased energy or wellbeing after donation. Some donors even report symptoms such as headache or feelings of unease indicating "it is time to donate blood again." This study aims to determine symptoms and frequencies of blood donors experiencing positive and negative effects of blood donation, and study possible associations with sex, age, body mass index, smoking status, and hemoglobin level.

Frequent blood donation and offspring scholastic attainment: an assessment of long-term consequences of prenatal iron deficiency.

Background: Due to physiological demands, children and premenopausal women are at risk of developing iron deficiency. In premenopausal women, the risk may be further increased by repeated whole blood donations. Short-term consequences of iron deficiency in infancy include impaired cognitive development and lower IQ scores.

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

Background: Blood donors have an increased risk of low hemoglobin (Hb) levels due to iron deficiency. Therefore, knowledge of genetic variants associated with low Hb could facilitate individualized donation intervals. We have previously reported three specific single-nucleotide polymorphisms that were associated with ferritin levels in blood donors.

Frequent blood donation and offspring birth weight-a next-generation association?

Background: The prevalence of iron depletion is high among premenopausal women who donate blood frequently. Studies in nondonor populations indicate that iron deficiency anemia is associated with an increased risk of low birth weight. This prompts concerns that iron deficiency induced by frequent blood donation might impair subsequent fetal development.

Restless legs syndrome is associated with major comorbidities in a population of Danish blood donors.

Background: Restless Legs Syndrome (RLS) is characterized by uncomfortable nocturnal sensations in the legs making sedentary activities and sleep difficult, and is thus linked with psychosocial distress. Due to the symptomatology and neurobiology of RLS (disrupting brain iron and dopamine) it is likely that RLS associates with poorer health-related quality of life (HRQL) and depressive disorder. The objective of this study was to investigate the RLS-HRQL and the RLS-depressive disorder links in a generally healthy population that is not biased by medications.

Calcium in drinking water: effect on iron stores in Danish blood donors-results from the Danish Blood Donor Study.

Background: Studies confirm that calcium inhibits iron absorption. Danish tap water comes from groundwater, which contains varying amounts of calcium depending on the subsoil. We investigated the association of calcium in drinking water with iron levels in Danish blood donors.

Reduced ferritin levels in individuals with non-O blood group: results from the Danish Blood Donor Study.

Background: Genomewide association studies have reported alleles in the ABO locus to be associated with ferritin levels. These studies warrant the investigation of a possible association between the ABO blood group and ferritin levels. We aimed to explore if ABO blood group is associated with iron stores expressed as ferritin levels.

Prevalence of restless legs syndrome and associated factors in an otherwise healthy population: results from the Danish Blood Donor Study.

Objective: Restless legs syndrome (RLS) is a neurological sensorimotor disorder characterized by uncomfortable sensations in the legs. RLS often occurs as a comorbid condition. Besides an increased risk of iron deficiency, blood donors are considered to be generally healthy.

Prevalence and correlation of cytokine-specific autoantibodies with epidemiological factors and C-reactive protein in 8,972 healthy individuals: Results from the Danish Blood Donor Study.

Natural cytokine-specific autoantibodies (c-aAb) have been measured in healthy and diseased individuals, and have been considered as both endogenous immune-regulators and pathogenic factors. Overall, the etiology and potential pathology of c-aAb are still undefined. To further characterize the sero-prevalence, predictors and consequences of high c-aAb levels, we performed the largest population-based study of c-aAb to date, using participants and epidemiological data from the Danish Blood Donor Study.

Deferral for low hemoglobin is not associated with increased risk of infection in Danish blood donors.

Background: Low hemoglobin (Hb) is associated with poor general health and adverse outcomes in a wide range of diseases. However, a link between Hb levels and the risk of infection among healthy individuals has yet to be investigated.

Study Design And Methods: Using data from the Scandinavian Donations and Transfusions database, 497,390 donors were followed after 5,458,499 donations in health registers.

Genetic factors influencing ferritin levels in 14,126 blood donors: results from the Danish Blood Donor Study.

Background: Many biologic functions depend on sufficient iron levels, and iron deficiency is especially common among blood donors. Genetic variants associated with iron levels have been identified, but the impact of genetic variation on iron levels among blood donors remains unclear.

Study Design And Methods: The effect of six single-nucleotide polymorphisms (SNPs) on ferritin levels in 14,126 blood donors were investigated in four genes: in Human Hemochromatosis Protein gene (HFE; rs1800562 and rs179945); in Transmembrane Protease gene, Serine 6 (TMPRSS6-regulating hepcidin; rs855791); in BTB domain containing protein gene (BTBD9-associated with restless legs syndrome; rs9357271); and in the Transferrin gene (TF; rs2280673 and rs1830084).

No association between iron status and self-reported health-related quality of life in 16,375 Danish blood donors: results from the Danish Blood Donor Study.

Background: Health-related quality of life (HRQL) represents people's subjective assessment of their mental and physical well-being. HRQL is highly predictive of future health. The effect of iron deficiency without anemia induced by blood donation on HRQL is presently unknown.

Predictors of hemoglobin in Danish blood donors: results from the Danish Blood Donor Study.

Background: It is well known that blood donors are at increased risk of iron deficiency and subsequent development of iron deficiency anemia. We aimed to investigate the effect of factors influencing hemoglobin (Hb) levels.

Study Design And Methods: Initiated in 2010, the Danish Blood Donor Study is a population-based study and biobank.

No association between rs6897932 in the gene encoding interleukin-7 receptor α and low-grade inflammation or self-reported health - results from the Danish Blood Donor Study.

The T-allele in the single nucleotide polymorphism rs6897932 in the gene encoding the IL-7 receptor α (IL7RA) is associated with reduced risk of autoimmune diseases including multiple sclerosis and also affects the course of HIV infection. Low-grade inflammation (LGI) and self-reported, health-related quality of life (HRQL) are often associated with chronic diseases and widely used in assessing and monitoring health status. The aim of the present study was to evaluate whether the T-allele in rs6897932 is associated with reduced risk of LGI (hsCRP 3-10 mg/L), history of infectious mononucleosis (IM), and HRQL in healthy individuals.

Combined oral contraception and obesity are strong predictors of low-grade inflammation in healthy individuals: results from the Danish Blood Donor Study (DBDS).

Background: C-reactive protein (CRP) is a well-established marker of inflammation. The level of CRP is affected by several lifestyle factors. A slightly increased CRP level, also known as low-grade inflammation (LGI), is associated with increased risk of several diseases, especially cardiovascular disease.

Predictors of iron levels in 14,737 Danish blood donors: results from the Danish Blood Donor Study.

Background: Dietary studies show a relationship between the intake of iron enhancers and inhibitors and iron stores in the general population. However, the impact of dietary factors on the iron stores of blood donors, whose iron status is affected by blood donations, is incompletely understood.

Study Design And Methods: In the Danish Blood Donor Study, we assessed the effect of blood donation frequency, physiologic factors, lifestyle and supplemental factors, and dietary factors on ferritin levels.