Heme carrier protein 1 (HCP1) genetic variants in the Hemochromatosis and Iron Overload Screening (HEIRS) Study participants

Heme carrier protein 1 (HCP1) has been identified as a possible heme carrier by in vitro analysis. To determine the association of mutations within the HCP1 gene with iron phenotypes, we examined the entire coding region of the HCP1 gene in 788 US and Canadian participants selected from the Hemochromatosis and Iron Overload Screening (HEIRS) Study using denaturing high-performance liquid chromatography. We sequenced the exon and flanking intronic regions if variants were detected. We tested 298 non-C282Y homozygotes from four racial/ethnic backgrounds (White, Black, Asian, and Hispanic) selected because they had high serum ferritin (SF) and transferrin saturations (TS). As controls, we chose 300 other random participants of the same racial/ethnic backgrounds from the same geographic locations. From the 333 HEIRS Study C282Y homozygotes, we selected 75 based on high SF and TS, 75 based on low SF and TS; and 75 were selected randomly as controls. Thirty-five of the randomly selected C282Y homozygotes were also included in the high and the low SF and TS groups due to numerical limitations. We identified eight different HCP1 genetic variants; each occurred in a heterozygous state. Except one, each was found in a single HEIRS Study participant. Thus, HCP1 variants are infrequent in the populations that we tested. Five HEIRS Study participants had non-synonymous, coding region HCP1 variants. Each of these five had TS above the 84th gender- and ethnic/racial group-specific percentile (TS percentiles: 84.7, 91.3, 97.9, 99.5, and 99.9).     

Tumor necrosis factor-alpha promoter variants and iron phenotypes in 785 Hemochromatosis and Iron Overload Screening (HEIRS) Study participants

We sought to determine if TNF promoter variants could explain iron phenotype heterogeneity in adults with previous HFE genotyping. HEIRS Study participants genotyped for C282Y and H63D were designated as high transferrin saturation (TS) and/or serum ferritin (SF) (high TS/SF), low TS/SF, or controls. We grouped 191 C282Y homozygotes as high TS/SF, low TS/SF, or controls, and 594 other participants by race/ethnicity as high TS/SF or controls. Using denaturing high-performance liquid chromatography (DHPLC), we screened the TNF promoter region in each participant. We performed multiple regression analyses in C282Y homozygotes using age, sex, HEIRS Study Field Center, and positivity for TNF ? 308G→A and ? 238G→A to determine if these attributes predicted ln TS or ln SF. DHPLC analyses were successful in 99.3% of 791 participants and detected 9 different variants; TNF ? 308G→A and ? 238G→A were the most prevalent. Most subjects positive for variants were heterozygous. The phenotype frequencies of each variant did not differ significantly (p < 0.05) across subgroups of C282Y homozygotes, or across white, black, Hispanic, and Asian non-C282Y homozygotes subgrouped as high TS/SF phenotypes and controls. TNF ? 308G→A positivity was a significant predictor of initial screening ln TS but not ln SF; TNF ? 238G→A predicted neither ln TS nor ln SF. We conclude that TNF promoter variants have little, if any, effect on initial screening SF values in adults with or without C282Y homozygosity. We cannot exclude a possible association of homozygosity for TNF promoter variants on TS and SF values.     

Hemochromatosis and Iron Overload Screening (HEIRS) study design for an evaluation of 100,000 primary care-based adults

BACKGROUND: The HEIRS Study will evaluate the prevalence, genetic and environmental determinants, and potential clinical, personal, and societal impact of hemochromatosis and iron overload in a multiethnic, primary care-based sample of 100,000 adults over a 5-year period. Participants are recruited from 5 Field Centers. Laboratory testing and data management and analysis are performed in a Central Laboratory and Coordinating Center, respectively. METHODS: Participants undergo testing for serum iron measures and common mutations of the hemochromatosis gene ( ) on chromosome 6p and answer questions on demographics, health, and genetic testing attitudes. Participants with elevated values of transferrin saturation and serum ferritin and/or C282Y homozygosity are invited to undergo a comprehensive clinical examination (CCE), as are frequency-matched control subjects. These examinations provide data on personal and family medical history, lifestyle characteristics, physical examination, genetic counseling, and assessment of ethical, legal, and social implications. Primary and secondary causes of iron overload will be distinguished by clinical criteria. Iron overload will be confirmed by quantification of iron stores. Recruiting family members of cases will permit DNA analysis for additional genetic factors that affect iron overload. RESULTS: Of the first 50,520 screened, 51% are white, 24% are African American, 11% are Asian, 11% are Hispanic, and 3% are of other, mixed, or unidentified race; 63% are female and 37% are male. CONCLUSIONS: Information from the HEIRS Study will inform policy regarding the feasibility, optimal approach, and potential individual and public health benefits and risks of primary care-based screening for iron overload and hemochromatosis.     

Serial serum ferritin measurements in untreated HFE C282Y homozygotes in the Hemochromatosis and Iron Overload Screening Study

Hemochromatosis has often been associated with progressive iron overload, but the natural history of iron accumulation in untreated C282Y homozygotes has been reported infrequently. The Hemochromatosis and Iron Overload Screening (HEIRS) Study screened 101 168 primary care participants for iron overload using transferrin saturation, unbound iron-binding capacity, Serum ferritin (SF), and HFE C282Y and H63D genotyping. SF was measured at initial screening (IS) and again when selected participants returned for a clinical examination (CE). The change in SF over the observation period (defined as ferritin rate of change) was analyzed according to age, gender, initial SF, initial SF/age, transferrin saturation, and iron removed by phlebotomy in C282Y homozygotes. Seventy-four male and 133 female untreated C282Y homozygotes were observed over a median of 112 days (34-924 days) between IS and CE. In men, SF increased in 54% and decreased in 46%. In women, SF increased in 50% and decreased in 50%. The significant variables affecting the SF rate were initial log SF (P = 0.0027) and transferrin saturation (P < 0.0001). Male C282Y homozygotes with higher SF rates (n = 27, upper 50th percentile) had significantly greater iron removed by phlebotomy (mean 4.93 g, range 1.0-17 g) than those with lower SF rates (n = 26, lower 50th percentile) (mean 2.6 g, 0.42-7.1, P < 0.05). SF was as likely to decrease as increase in untreated C282Y homozygotes over this relatively brief observation period. Incremental increases in SF are not inevitable in untreated C282Y homozygotes.     

Serum ferritin is a biomarker for liver mortality in the Hemochromatosis and Iron Overload Screening Study

Background. We identified no reports of long-term follow-up of participants in hemochromatosis screening programs. We evaluated causes of death and survival in non-C282Y homozygous Canadian participants in the primary care-based hemochromatosis and iron overload screening (HEIRS) study.Material and methods. Initial screening (IS) included transferrin saturation (TS), serum ferritin (SF), HFE genotyping (C282Y, H63D), and health questionnaire responses. By definition, participants without C282Y or H63D had HFE wt/wt. We linked 20,306 Canadian participants to the Ontario Death Registry for dates and causes of death 9 y after IS. We computed Cox proportional hazards to identify factors with increased death risks and Kaplan-Meier curves to estimate survival of non-C282Y homozygous participants with SF ≤ 1,000 µg/L and > 1,000 µg/dL.Results. There were 19,052 evaluable participants (IS mean age 49 y; 60% women; 93 C282Y homozygotes). There were 988 deaths. Significantly increased hazard ratios for all-cause mortality were positively associated with TS, SF, men, and C282Y homozygosity, and liver disease, diabetes, and heart failure reports. Non-C282Y homozygous participants with SF > 1,000 µg/L had lower survival than those with SF ≤ 1,000 µg/L (p < 0.0001).Conclusions. Nine years after initial screening, non-C282Y homozygous participants and SF > 1,000 µg/L was associated with decreased survival.     

Screening for iron overload: Lessons from the HEmochromatosis and IRon Overload Screening (HEIRS) Study

BACKGROUND:

The HEmochromatosis and IRon Overload Screening (HEIRS) Study provided data on a racially, ethnically and geographically diverse cohort of participants in North America screened from primary care populations.

METHODS:

A total of 101,168 participants were screened by testing for HFE C282Y and H63D mutations, and measuring serum ferritin concentration and transferrin saturation. In the present review, lessons from the HEIRS Study are highlighted in the context of the principles of screening for a medical disease as previously outlined by the World Health Organization.

RESULTS:

Genetic testing is well accepted, with minimal risk of discrimination. Transferrin saturation has high biological variability and relatively low sensitivity to detect HFE C282Y homozygotes, which limits its role as a screening test. Symptoms attributable to HFE C282Y homozygosity are no more common in individuals identified by population screening than in control subjects.

CONCLUSIONS:

Generalized population screening in a primary care population as performed in the HEIRS Study is not recommended. There may be a role for focused screening in Caucasian men, with some debate regarding genotyping followed by phenotyping, or phenotyping followed by genotyping.     

Ferroportin (Q248H) mutations in African families with dietary iron overload

BACKGROUND: Dietary iron overload found in sub-Saharan Africa might be caused by an interaction between dietary iron and an iron-loading gene. Caucasian people with ferroportin gene mutations have iron overload histologically similar to that found in African patients with iron overload. Ferroportin is also implicated in the hypoferremic response to inflammation. The prevalence of the ferroportin Q248H mutation, unique to African people, and its association with dietary iron overload, mean cell volume (MCV) and C-reactive protein (CRP) were examined in 19 southern African families. METHODS: Polymerase chain reaction (PCR) and restriction enzyme digestion were used to identify the Q248H mutation. Statistical analysis was carried out to correlate the presence of the mutation with markers of iron overload and inflammation. RESULTS: We identified three (1.4%) Q248H homozygotes and 53 (24.1%) heterozygotes in the families examined in the present study. There was no increased prevalence of the mutation in index subjects or their families. Logistic regression showed significantly higher serum ferritin concentrations with the mutation. The mean cell volume (MCV) was significantly lower, and the serum CRP significantly higher in subjects who carried the mutation. CONCLUSIONS: The present study of 19 families with African iron overload failed to show evidence that the ferroportin (Q248H) mutation is responsible for the condition. Logistic regression, correcting for factors influencing iron status, did show increased ferritin levels in individuals with the mutation. The strong association with low MCV suggests the possibility that the ferroportin (Q248H) mutation might interfere with iron supply, whereas the elevated serum CRP might indicate that the ferroportin mutation influences the inflammatory response in African populations.     

Ferroportin (SLC40A1) Q248H mutation is associated with lower circulating serum hepcidin levels in Rwandese HIV-positive women

The Q248H mutation in the gene SLC40A1 which encodes for the cellular iron exporter ferroportin is relatively common in Africa. This mutation has been associated with resistance to hepcidin and therefore we hypothesized that iron-related parameters and the prevalence of opportunistic infections in HIV might be influenced by the Q248H mutation. We conducted a cross-sectional study among 200 HIV-positive women in the Butare University Teaching Hospital in Rwanda. Polymerase chain reaction (PCR) and restriction enzyme digestion were used to identify the Q248H mutation. Physical examination was carried out and WHO HIV disease stage classification, complete blood count, CD4 count, indirect measures of iron status, serum hepcidin, and C-reactive protein concentrations were determined. The prevalence of ferroportin Q248H mutation was 6%. Subjects with ferroportin Q248H mutation had significantly higher values for serum ferritin (P = 0.001) and significantly lower values for serum hepcidin (P = 0.001) and transferrin (P = 0.01). Among the 12 HIV + Q248H heterozygotes, 8 suffered from at least one opportunistic infection. There was significantly higher prevalence of pulmonary TB (P = 0.01) and Pneumocystis jiroveci pneumonia (P = 0.02) in subjects with ferroportin Q248H mutation. Low hepcidin levels were found in ferroportin Q248H heterozygotes with HIV infection, notwithstanding the absence of anemia and the higher prevalence of some opportunistic infections. Hepcidin seems to be regulated in a different way in Q248H heterozygotes than is known thus far.     

Association of Gln222Arg polymorphism in the deoxyribonuclease I (DNase I) gene with myocardial infarction in Japanese patients.

AIMS: We have recently reported that serum deoxyribonuclease I (DNase I) activity, which may be involved in apoptosis, increases abruptly in the early phase of acute myocardial infarction (MI) [Kawai Y, Yoshida M, Arakawa K, Kumamoto T, Morikawa N, Masamura K, Tada H, Ito S, Hoshizaki H, Oshima S, Taniguchi K, Terasawa H, Miyamori I, Kishi K, Yasuda T. Diagnostic use of serum deoxyribonuclease I activity as a novel early-phase marker in acute myocardial infarction. Circulation 2004;109:2398-2400]. Death of vascular smooth muscle cells, in part because of apoptosis, is postulated to heighten susceptibility to disruption of vulnerable plaque, resulting in onset of MI. The present study evaluated the possibility that Gln222Arg polymorphism of the DNase I gene may be one of the factors involved in predisposition to MI. METHODS AND RESULTS: We assessed 611 Japanese patients: 311 with MI and 300 with stable angina pectoris (AP). Three common phenotypes determined by two common codominant alleles, DNASE1*1 and *2, whose corresponding gene products exhibit different properties, were found in these patient groups. The prevalence of DNASE1*2 was significantly higher in patients with MI than in those with AP (0.543 vs. 0.428, P < 0.001), being confirmed by phenotyping of the second study population. Multiple logistic regression analysis showed that the odds ratio of DNASE1*2 was 1.51 [95% confidence interval (CI) 1.04-2.18]. The association of the DNASE1*2 allele with MI was statistically significant, being independent of other conventional risk factors. CONCLUSION: Our data demonstrate that Gln222Arg polymorphism in the DNase I gene is associated with MI in the Japanese patients.     

Complement factor H (Y402H) polymorphism and risk of coronary heart disease in US men and women.

AIMS: Complement factor H (CFH) Y402H polymorphism is located in a region that binds C-reactive protein and may affect inflammatory processes and risk of coronary heart disease (CHD). We assessed the association between Y402H and risk of CHD in nested case-control studies among two large prospective cohorts of US male health professionals and female nurses. METHODS AND RESULTS: Among participants who were disease-free at baseline, we confirmed 266 (men) and 249 (women) incident CHD deaths and non-fatal myocardial infarctions (MIs) over 6 and 8 years of follow-up, respectively. Using risk-set sampling, controls were matched 2:1 on the basis of age, smoking, and date of blood draw. Comparing homozygous HH with YY, the relative risk (RR) of CHD was 0.94 [95% confidence interval (CI) 0.59-1.49] among men and 0.51 (95% CI 0.29-0.89) among women (pooled RR 0.73, 95% CI 0.51-1.04). The HH genotype was inversely associated with CHD among those <65 years at onset (men: RR 0.39, 95% CI 0.16-0.95; women: 0.21, 95% CI 0.07-0.65; pooled: 0.30, 95% CI 0.15-0.61), but not among those > or =65 years (pooled RR 1.09, 95% CI 0.71-1.68). CONCLUSION: CFH Y402H was inversely associated with CHD among women, but not men. This inverse association was observed in both populations with earlier age of CHD.     

Association between variants in the genes for adiponectin and its receptors with insulin resistance syndrome (IRS)-related phenotypes in Mexican Americans

Aims/hypothesis The aim of this study was to examine whether genetic variation in ADIPOQ, ADIPOR1 and ADIPOR2 may contribute to increased susceptibility to components of the insulin resistance syndrome (IRS). Materials and methods We genotyped single-nucleotide polymorphisms (SNPs) in ADIPOQ, ADIPOR1 and ADIPOR2 in Mexican American subjects (N=439) and performed an association analysis of IRS-related traits. Results Of the eight SNPs examined in the ADIPOQ gene, rs4632532 and rs182052 exhibited significant associations with BMI (p=0.029 and p=0.032), fasting specific insulin (p=0.023 and p=0.026), sum of skin folds (SS) (p=0.0089 and p=0.0084) and homeostasis model assessment of insulin sensitivity (HOMA-%S) (p=0.015 and p=0.016). Two other SNPs, rs266729 and rs2241767, were significantly associated with SS (p=0.036 and p=0.013). SNP rs7539542 of ADIPOR1 was significantly associated with BMI, SS and waist circumference (p=0.025, p=0.047 and p=0.0062). Fourteen of the ADIPOR2 SNPs were found to be significantly (p<0.05) associated with fasting plasma triglyceride concentrations. Four of these SNPs (rs10848569, rs929434, rs3809266 and rs12342) were in high pairwise linkage disequilibrium (r ²=0.99) and were strongly associated with fasting triglyceride levels (p=0.00029, p=0.00016, p=0.00027 and p=0.00021). Adjusting for the effects of BMI and HOMA-%S on triglyceride concentrations increased significance to p=0.000060 for SNP rs929434. Bayesian quantitative trait nucleotide analysis was used to examine all possible models of gene action. Again, SNP rs929434 provided the strongest statistical evidence of an effect on triglyceride concentrations. Conclusions/interpretation These results provide evidence for association of SNPs in ADIPOQ and its receptors with multiple IRS-related phenotypes. Specifically, several genetic variants in ADIPOR2 were strongly associated with decreased triglyceride levels.     

甲亢与甲减患者血浆同型半胱氨酸水平和MTHFR基因多态性研究

本研究观察了 5 0名正常人 ,3 2例甲状腺功能减退 (甲减 )患者和 48例甲状腺功能亢进 (甲亢 )患者血浆同型半胱氨酸 (Hcy)水平和 5 ,10 亚甲基四氢叶酸还原酶 (MTHFR)基因的多态性。与正常组相比 ,血浆Hcy水平在甲减组升高 (P <0 .0 1) ,而在甲亢组降低 (P <0 .0 5 ) ;在不同甲状腺功能人群中血浆Hcy水平与FT4水平呈负相关 (r =-0 .3 5 ,P <0 .0 1)。在 3组对象中 ,MTHFR均以C/C基因型为主 ,各基因型 (C/C ,C/T ,T/T)、各等位基因 (C ,T)分布差异无显著性 ,但各组中T/T基因型者血浆Hcy水平均高于同组的其它基因型 (P <0 .0 1)。     

Association of West African ancestry and blood pressure control among African Americans taking antihypertensive medication in the Jackson Heart Study

African Americans have a wide range of continental genetic ancestry. It is unclear whether racial differences in blood pressure (BP) control are related to ancestral background. The authors analyzed data from the Jackson Heart Study, a cohort exclusively comprised of self‐identified African Americans, to assess the association between estimated West African ancestry (WAA) and BP control (systolic and diastolic BP < 140/90 mm Hg). Three nested modified Poisson regression models were used to calculate prevalence ratios for BP control associated with the three upper quartiles, separately, vs the lowest quartile of West African ancestry. The authors analyzed data from 1658 participants with hypertension who reported taking all of their antihypertensive medications in the previous 24 hours. WAA was estimated using 389 ancestry informative markers and categorized into quartiles (Q1: <73.7%, Q2: >73.7%‐81.0%, Q3: >81.0%‐86.3%, and Q4: >86.3%). The proportion of participants with controlled BP in the lowest‐to‐highest WAA quartile was 75.2%, 76.1%, 76.6%, and 74.4%. The prevalence ratios (95% CI) for controlled BP comparing Q2, Q3, and Q4 to Q1 of WAA were 1.00 (0.93‐1.08), 1.02 (0.94‐1.10), and 0.99 (0.91‐1.07), respectively. Among African Americans in the Jackson Heart Study taking antihypertensive medication, BP control rates did not differ across quartiles of WAA.     

Association of K121Q polymorphism in ENPP1 (PC-1) with BMI in Caucasian and African-American adults

OBJECTIVE: To test for association of the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) K121Q polymorphism with body mass index (BMI) and diabetes in a large sample of Caucasians and African-Americans by selectively genotyping individuals at the extremes of the phenotypic distribution. SUBJECTS: Subsets comprising the extremes of the BMI distribution (10th-20th and above the 90th BMI percentile for Caucasians and between the 10th-30th and above the 80th percentile for African-Americans) from a group of 10,260 Caucasian and 2268 African-American adults participating in New York Cancer Project were studied. METHODS: Subjects were genotyped for the ENPP1 K121Q polymorphism by pyrosequencing and tested for association with BMI and diabetes by regression analysis. RESULTS: Regression analysis with BMI as the dependent variable demonstrated a significant association (P = 0.02) of genotype at K121Q with BMI, with no significant race-by-genotype interaction (P = 0.30). Compared with Q/Q or Q/K individuals, the K/K individuals had a BMI approximately 1.3 kg/m2 higher, without effects of age, gender or race. By logistic regression analysis, the K121Q alleles had no significant effect on diabetes status (P = 0.37) in obese subjects. CONCLUSION: In both Caucasians and African-Americans, the K121 polymorphism in ENPP1 was associated with increased BMI, but not with diabetes.     

Apolipoprotein B (apo B) signal peptide length polymorphisms are associated with apo B, low density lipoprotein cholesterol, and glucose levels in Mexican Americans

We investigated the effects of apolipoprotein (apo) B signal peptide length polymorphisms on low density lipoprotein cholesterol (LDL-C), apo B, and post-challenge (2 h) glucose levels in 686 Mexican Americans from 34 families. The most common allele encoded an apo B signal peptide of 27 amino acids (ins; SP-27), the next most frequent allele encoded a 24 amino acid signal peptide (del; SP-24), and the rarest allele encoded a 29 amino acid signal peptide (ins^*; SP-29) that has been found only in Mexican Americans. Homozygotes for the SP-24 allele had significantly higher mean levels of apo B, LDL-C, and 2-h glucose than SP-27 homozygotes, and SP-27/SP-24 heterozygotes had intermediate levels (P = 0.01 for apo B, P < 0.001 for LDL-C, and P = 0.04 for 2-h glucose). Heterozygotes for the SP-29 allele had higher apo B and LDL-C levels compared to homozygotes for the SP-27 or SP-24 alleles. Apo B signal peptide length polymorphism accounted for 4.2%, 3.5%, and 3.0% of the residual variation in LDL-C, apo B, and 2-h glucose levels, respectively, among the Mexican American families.     

E选择素A561C基因多态性与老年人心肌梗死和血脂的相关分析

目的 探讨中国湖北武汉地区E选择素基因A561C多态性与老年人心肌梗死的相关性，并对其与血脂、脂蛋白水平的关系进行分析。方法 应用聚合酶链反应和限制性片段长度多态性(PCR-RFLP)技术检测198例老年心肌梗死患者、187例中青年心肌梗死患者和190例老年健康对照者、185例中青年健康对照者E-选择素基因型，并按常规方法测定血脂水平。结果 E-选择素等位基因A、C频率在老年心肌梗死组和中青年心肌梗死组分别为：92．9％、7．1％和93．3％、6．7％；在老年健康对照组和中青年健康对照组分别为96．6％、3．4％和96.8％、3．2％，同龄梗死组与非梗死组间比较，差异有显著性(P＜0．05)。基因型频率分布符合Hardy-weinberg平衡定律。老年、中青年心肌梗死组分别与老年、中青年健康对照组比较，其基因型频率差异有显著性(均P＜0．05)；老年、中青年心肌梗死组血浆总胆固醇(TC)、甘油三酯(TG)和低密度脂蛋白胆固醇(LDL-C)均高于老年、中青年健康对照组(P＜0．05)。结论 E-选择素A561C基因多态性与老年心肌梗死的发病有关，C等位基因可能是心肌梗死发病的危险因素之一。     

Association between serum 25 (OH) D levels and depression symptoms in adults with prediabetes

Background and aimDepression symptoms are a significant risk factor for prediabetes-related diabetes, and low vitamin D levels are connected with depression symptoms. The goal of this study is to examine the association between vitamin D and depression symptoms in prediabetic persons.MethodsThis cross-sectional survey was conducted in Tianjin, China, among 4051 individuals. Symptoms of depression were assessed using the Self-Rating Depression Scale (SDS) (cut-off point SDS ≥45). Serum 25 (OH) D concentrations were determined using an enzyme immunoassay (OCTEIA 25-hydroxy Vitamin D, IDS Ltd, UK) and classified into three levels: 50 nmol/L, 50–75 nmol/L, and >75 nmol/L. The link between serum 25 (OH) D concentrations and depression symptoms in prediabetes was investigated using multiple logistic regression analysis. The models were adjusted for a variety of potential confounders.ResultsThe prevalence of symptoms of depression in prediabetic adults was 14.2% (12.5% males and 16.4% females). After adjusting for potentially confounding variables, the odds ratios - ORs for symptoms of depression in women across serum 25 (OH) D levels were 1.00 (reference), 1.03 (0.57, 1.39), and 0.28 (0.12, 0.57), respectively (p = 0.0015). However, no statistically significant connection was discovered in males.ConclusionIn women with prediabetes, we showed a substantial negative connection between serum 25 (OH) D levels and depressed symptoms. Vitamin D supplementation may be an effective way to decrease the risk of depression symptoms in women with prediabetes.