The impact of H63D HFE gene carriage on hemoglobin and iron status in children

Association of iron supplementation, HFE and AMPD1 polymorphisms and biochemical iron metabolism parameters in the performance of a men's World Tour cycling team: A pilot study

BACKGROUND

Nutritional strategies with iron supplementation have been shown to be effective in preventing the decline of blood biochemical parameters and sports performance. The aim of the study was to describe biochemical iron metabolism parameters in association with iron supplementation and HFE and AMPD1 polymorphisms in a Union Cycliste Internationale (UCI) World Tour cycling team to evaluate performance during a whole season METHODS: Twenty-eight professional men cyclists took part in this longitudinal observational pilot study. AMPD1 c.34 C>T (rs17602729) and HFE c.187 C>G (rs1799945) polymorphisms were genotyped using Single Nucleotide Primer Extension (SNPE). All the professional cyclists took oral iron supplementation throughout the season. Four complete blood analyses were carried out corresponding to UCI controls in January (1st), April (2nd), June (3rd) and October (4th). Data on participation in three-week Grand Tours, kms of competition and wins were analyzed.

RESULTS

In performance, especially in wins, there was a significant effect in HFE on biochemical hemoglobin (F = 4.255; p = 0.021) and biochemical hematocrit (F = 5.335; p = 0.009) and a hematocrit biochemical × genotype interaction (F = 3.418; p = 0.041), with higher values in professional cyclist with GC genotype. In AMPD1 there were significant effects in the biochemical iron x genotype interaction in three-week Grand Tours (F = 3.874; p = 0.029) and wins (F = 3.930; p = 0.028) CONCLUSIONS: Blood biochemical iron metabolism parameters could be related to performance in the season due to increasing hemoglobin and hematocrit concentration under iron supplementation, associated with winning in the professional cyclists with GC genotype of the HFE polymorphism.

Genetic profiles to identify talents in elite endurance athletes and professional football players

The genetic profile that is needed to identify talents has been studied extensively in recent years. The main objective of this investigation was to approach, for the first time, the study of genetic variants in several polygenic profiles and their role in elite endurance and professional football performance by comparing the allelic and genotypic frequencies to the non-athlete population. In this study, genotypic and allelic frequencies were determined in 452 subjects: 292 professional athletes (160 elite endurance athletes and 132 professional football players) and 160 non-athlete subjects. Genotyping of polymorphisms in liver metabolisers (CYP2D6, GSTM1, GSTP and GSTT), iron metabolism and energy efficiency (HFE, AMPD1 and PGC1a), cardiorespiratory fitness (ACE, NOS3, ADRA2A, ADRB2 and BDKRB2) and muscle injuries (ACE, ACTN3, AMPD1, CKM and MLCK) was performed by Polymerase Chain Reaction-Single Nucleotide Primer Extension (PCR-SNPE). The combination of the polymorphisms for the “optimal” polygenic profile was quantified using the genotype score (GS) and total genotype score (TGS). Statistical differences were found in the genetic distributions between professional athletes and the non-athlete population in liver metabolism, iron metabolism and energy efficiency, and muscle injuries (p<0.001). The binary logistic regression model showed a favourable OR (odds ratio) of being a professional athlete against a non-athlete in liver metabolism (OR: 1.96; 95% CI: 1.28–3.01; p = 0.002), iron metabolism and energy efficiency (OR: 2.21; 95% CI: 1.42–3.43; p < 0.001), and muscle injuries (OR: 2.70; 95% CI: 1.75–4.16; p < 0.001) in the polymorphisms studied. Genetic distribution in professional athletes as regards endurance (professional cyclists and elite runners) and professional football players shows genetic selection in these sports disciplines.

Exome sequencing for diagnosis of congenital hemolytic anemia

Background

Congenital hemolytic anemia constitutes a heterogeneous group of rare genetic disorders of red blood cells. Diagnosis is based on clinical data, family history and phenotypic testing, genetic analyses being usually performed as a late step. In this study, we explored 40 patients with congenital hemolytic anemia by whole exome sequencing: 20 patients with hereditary spherocytosis and 20 patients with unexplained hemolysis.

Results

A probable genetic cause of disease was identified in 82.5% of the patients (33/40): 100% of those with suspected hereditary spherocytosis (20/20) and 65% of those with unexplained hemolysis (13/20). We found that several patients carried genetic variations in more than one gene (3/20 in the hereditary spherocytosis group, 6/13 fully elucidated patients in the unexplained hemolysis group), giving a more accurate picture of the genetic complexity of congenital hemolytic anemia. In addition, whole exome sequencing allowed us to identify genetic variants in non-congenital hemolytic anemia genes that explained part of the phenotype in 3 patients.

Conclusion

The rapid development of next generation sequencing has rendered the genetic study of these diseases much easier and cheaper. Whole exome sequencing in congenital hemolytic anemia could provide a more precise and quicker diagnosis, improve patients’ healthcare and probably has to be democratized notably for complex cases.

Genotype scores in energy and iron-metabolising genes are higher in elite endurance athletes than in nonathlete controls

Information about the association of energy and iron-metabolising genes with endurance performance is scarce. The objective of this investigation was to compare the frequencies of polymorphic variations of genes involved in energy generation and iron metabolism in elite endurance athletes versus nonathlete controls. Genotype frequencies in 123 male elite endurance athletes (75 professional road cyclists and 48 elite endurance runners) and 122 male nonathlete participants were compared by assessing 4 genetic polymorphisms: AMPD1 c.34C/T (rs17602729), PPARGC1A c.1444G/A (rs8192678) HFE_H63D c.187C/G (rs1799945) and HFE_C282Y c.845G/A (rs1800562). A weighted genotype score (w-TGS; from 0 to 100 arbitrary units (a.u.)) was calculated by assigning a corresponding weight to each polymorphism. In the nonathlete population, the mean w-TGS value was lower (39.962 ± 14.654 a.u.) than in the group of elite endurance athletes (53.344 ± 17.053 a.u). The binary logistic regression analysis showed that participants with a w-TGS > 38.975 a.u had an odds ratio of 1.481 (95% confidence interval: 1.244-1.762; p < 0.001) for achieving elite athlete status. The genotypic distribution of polymorphic variations involved in energy generation and iron metabolism was different in elite endurance athletes vs. controls. Thus, an optimal genetic profile in these genes might contribute to physical endurance in athlete status. Novelty Genetic profile in energy generation and iron-metabolising genes in elite endurance athletes is different than that of nonathletes. There is an implication of an "optimal" genetic profile in the selected genes favouring endurance sporting performance.

The association of HFE gene H63D polymorphism with endurance athlete status and aerobic capacity: novel findings and a meta-analysis

PURPOSE

Iron is an important component of the oxygen-binding proteins and may be critical to optimal athletic performance. Previous studies have suggested that the G allele of C/G rare variant (rs1799945), which causes H63D amino acid replacement, in the HFE is associated with elevated iron indexes and may give some advantage in endurance-oriented sports. The aim of the present study was to investigate the association between the HFE H63D polymorphism and elite endurance athlete status in Japanese and Russian populations, aerobic capacity and to perform a meta-analysis using current findings and three previous studies.

METHODS

The study involved 315 international-level endurance athletes (255 Russian and 60 Japanese) and 809 healthy controls (405 Russian and 404 Japanese). Genotyping was performed using micro-array analysis or by PCR. VO2max in 46 male Russian endurance athletes was determined using gas analysis system.

RESULTS

The frequency of the iron-increasing CG/GG genotypes was significantly higher in Russian (38.0 vs 24.9%; OR 1.85, P = 0.0003) and Japanese (13.3 vs 5.0%; OR 2.95, P = 0.011) endurance athletes compared to ethnically matched controls. The meta-analysis using five cohorts (two French, Japanese, Spanish, and Russian; 586 athletes and 1416 controls) showed significant prevalence of the CG/GG genotypes in endurance athletes compared to controls (OR 1.96, 95% CI 1.58-2.45; P = 1.7 × 10-9). Furthermore, the HFE G allele was associated with high V̇O2max in male athletes [CC: 61.8 (6.1), CG/GG: 66.3 (7.8) ml/min/kg; P = 0.036].

CONCLUSIONS

We have shown that the HFE H63D polymorphism is strongly associated with elite endurance athlete status, regardless ethnicities and aerobic capacity in Russian athletes.

The p.H63D allele of the HFE gene protects against low iron stores in Sri Lanka

In hereditary hemochromatosis, iron overload is associated with homozygosity for the p.C282Y mutation. A second mutation, p.H63D, occurs at significant frequencies in Europe, North Africa, the Middle East and Asia. Early studies in Sri Lanka indicated that the variant had arisen independently, suggesting that it had been the subject of selective pressure. However, its role in iron absorption is unclear. In a survey of 7526 Sri Lankan secondary school students, we determined hemoglobin genotype and measured red cell indices, serum ferritin, transferrin receptor, iron zinc protoporphyrin and hepcidin. These variables were compared according to the presence or absence of the p.H63D variant in a subset of 1313 students for whom DNA samples were available. Students were classified as having low red cell indices if they had an MCV <80 fl and/or MCH <27 pg. Hetero and/or homozygosity for the p.H63D variant was more common in students with normal than low red cell indices (16.4% and 11.9% respectively; p = 0.019). Iron biomarkers and red cell indices were greater in children with the p.H63D variant than in normal and this was statistically significant for MCV (p = 0.046). Our findings suggest that selective pressure by mild iron deficiency contributes to the high frequencies of the p.H63D variant.

Interactive Effects between Chronic Lead Exposure and the Homeostatic Iron Regulator Transport HFE Polymorphism on the Human Red Blood Cell Mean Corpuscular Volume (MCV)

Research has shown that long-term exposure to lead harms the hematological system. The homeostatic iron regulator HFE (hemochromatosis) mutation, which has been shown to affect iron absorption and iron overload, is hypothesized to be related to lead intoxication in vulnerable individuals. The aim of our study was to investigate whether the HFE genotype modifies the blood lead levels that affect the distributions of serum iron and other red blood cell indices. Overall, 121 lead workers and 117 unexposed age-matched subjects were recruited for the study. The collected data included the blood lead levels, complete blood count, serum iron, total iron binding capacity, transferrin, and ferritin, which were measured during regular physical examinations. All subjects filled out questionnaires that included demographic information, medical history, and alcohol and tobacco consumption. HFE genotyping for C282Y and H63D was determined using polymerase chain reaction and restriction fragment length polymorphism (PCR/RFLP). The mean blood lead level in lead workers was 19.75 µg/dL and was 2.86 µg/dL in unexposed subjects. Of 238 subjects, 221 (92.9%) subjects were wild-type (CCHH) for HFE C282Y and H63D, and 17 (7.1%) subjects were heterozygous for a H63D mutation (CCHD). Multiple linear regression analysis showed that blood lead was significantly negatively associated with hemoglobin (Hb), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular volume (MCV), whereas the HFE variant was associated negatively with MCV and positively with ferritin. An interactive influence on MCV was identified between blood lead and HFE variants. Our research found a significant modifying effect of the HFE variant, which possibly affected MCV. The HFE H63D heterozygous (CCHD) variant seemed to provide a protective factor against lead toxicity. Future studies should focus on competing binding proteins between iron and lead influenced by gene variation.

Reduction of Skeletal Muscle Power in Adolescent Males Carrying H63D Mutation in the HFE Gene

Iron overload resulting from the mutation of genes involved in iron metabolism or excess dietary intake has been reported to negatively influence human physical performance. The aim of this study was to test the hypothesis that adolescents bearing a hemochromatosis gene (HFE) mutation in contrast to adults with the same mutation will not experience iron accumulation and their aerobic capacity will be similar to that of age-matched controls. Thirteen boys participated in the study. Seven of them are carriers of H63D mutation in the HFE gene and six were wild type. Fitness levels were assessed using the cardiopulmonary exercise test. In addition, iron status and inflammatory markers were determined. We observed that cardiovascular fitness was significantly lower in the group bearing the HFE mutation compared to the control group. Moreover, the HFE mutation group achieved lower maximal power output compared to the control group. There were no differences in blood ferritin concentrations between the two groups which indicates similar amounts of stored iron. Obtained data do not confirm our hypothesis. On the contrary, it was demonstrated that HFE mutation is associated with a lower level of aerobic capacity, even in the absence of iron accumulation.

[Hfeprotein impact on iron metabolism]

Hereditary hemochromatosis type 1 is an autosomal recessive disorder caused by HFE gene mutations, which is an iron homeostasis metabolism controlling co-factor. Adults with male predomination present with clinical symptoms derived by iron overload in organs. The phenotype expression is individual with an influence of individual and environmental factors. Despite the fact that HFE variants are widespread, its impact still remains unknown. The article reviews the literature considering the role of HFE gene mutations regarding its impact in children.