fetuin-A Research Articles

Serum Fetuin-A Levels Are Associated with Vascular Calcifications and Predict Cardiovascular Events in Renal Transplant Recipients

Vascular calcifications predict cardiovascular disease, the major cause of death in renal transplant recipients (RTRs). We studied the determinants of fetuin-A, a potent circulating calcification inhibitor encoded by the AHSG gene, and tested its association with vascular calcifications and long-term survival and cardiovascular events (CVEs) in RTRs. Two hundred seventy-seven prevalent RTRs from a single center were included. CVEs and deaths were prospectively recorded during a 5-year follow-up. Independent determinants of lower serum fetuin-A levels were lower plasma cholesterol, the AHSG rs4918 G allele, and history of smoking. Low serum fetuin-A level was a determinant of aortic calcifications (assessed using spiral CT). Low fetuin-A levels (≤0.47 g/L, first quintile) were independently associated with CVEs and deaths (hazard ratio=1.83; 95% confidence interval, 1.07 to 3.04). The association was confirmed for all-cause mortality, and the major adverse cardiovascular endpoints were analyzed separately. Patients with low fetuin-A and high high-sensitivity C-reactive protein (>4.36 mg/L, fourth quintile) levels had a 3.5-fold increased risk of all-cause mortality and CVEs. In the presence of inflammation, CVE-free survival was influenced by common variants in the AHSG gene. These data show that low fetuin-A levels are independently associated with aortic calcifications and a higher risk of CVEs and mortality. They support fetuin-A as a circulating biomarker able to identify RTRs at risk for vascular calcifications and CVEs.

Role of Fetuin-A in Systemic Sclerosis-associated Calcinosis

To the Editor: Calcinosis, a soft-tissue calcification occurring in the setting of normal serum calcium and phosphate levels, has been observed in connective tissue diseases, including systemic sclerosis (SSc)1, more frequently in the limited form (lcSSc) and in patients who are anticentromere antibody (ACA)-positive1. Calcinosis may be exceedingly painful and cause major clinical problems, including ulceration, infection, and joint contractures1. Hypovascularity, hypoxia, and tissue damage seem to favor its development, with genetic factors also playing a role. No treatment exists so far, and even surgical removal is unsatisfactory, since recurrences are common1. Fetuin-A (α-2-Heremans-Schmid glycoprotein, AHSG) is a major inhibitor of systemic calcification, and low serum levels have been associated with vascular and soft-tissue calcifications2. Any situation that lowers serum fetuin-A, including inflammatory conditions, could increase the risk of calcification, because fetuin-A is a negative acute-phase protein. AHSG gene variations seem to influence fetuin-A serum concentration3. Forty-one consecutive Italian patients with SSc [40 women, age 63 ± 13 years, 16 diffuse SSc (dcSSc), 25 lcSSc] were … Address correspondence to Dr. L. Belloli, Via Manzoni 56, Rozzano 20089, Italy. E-mail: laurabelloli{at}tiscali.it

Is fetuin-A a mortality risk factor in dialysis patients or a mere risk marker? A Mendelian randomization approach

Low levels of circulating fetuin-A are associated with increased mortality in dialysis patients. This study aimed to examine a potential causative role for fetuin-A on mortality by investigating whether a functional polymorphism in the alpha2-Heremans-Schmid glycoprotein (AHSG) gene associates with mortality, and by estimating the causative effect of fetuin-A levels on mortality using a Mendelian randomization design. One thousand and forty-three incident dialysis patients were genotyped for the Thr256Ser polymorphism (rs4918) and followed up for 5 years; in 549 patients, serum fetuin-A levels were measured. Carriers of a serine allele displayed lower fetuin-A levels (-0.07 g/L per allele, P < 0.001). A small increased mortality risk was observed for the Thr/Ser and Ser/Ser genotype compared with the Thr/Thr genotype (HR 1.03, 95% CI 0.83-1.28 and HR 1.10, 95% CI 0.78-1.55, respectively). Using the AHSG genotype as an instrumental variable, the causative HR of fetuin-A levels on mortality was estimated as 1.01 per 0.1-g/L increase. Inflammation and diabetes partially modified the association of fetuin-A levels with outcome. The Thr256Ser polymorphism was weakly associated with mortality, and no causative effect of fetuin-A levels on this outcome was observed. Other risk factors, including inflammation and diabetes, might lead to lower fetuin-A levels, and/or modify the effect of low fetuin-A on mortality in end-stage renal disease patients.

Association of alpha 2-Heremans-Schmid glycoprotein gene polymorphisms with its serum levels

To identify the single nucleotide polymorphisms (SNPs) of the alpha2-Heremans-Schmid glycoprotein (AHSG) gene and assess their association with the AHSG serum level. The SNPs of the AHSG gene were identified from 30 unrelated Han individuals from Guangzhou area by resequencing. Linkage disequilibrium(LD) was performed to observe the linkage disequilibrium pattern. Then tagSNPs were genotyped in 192 Han individuals from Beijing and 424 Han individuals from Guangzhou area. Finally, luciferase reporter gene assay was performed to determine whether the SNPs affected the promoter activity. Serum AHSG concentrations were measured in the 192 subjects from Beijing using ELISA. Eight SNPs were detected in total. The linkage disequilibrium profile in the Guangzhou Han population was different from that in the Beijing Han population. However, the allele and genotype frequencies of tagSNPs between the two Han populations were not significantly different. The reporter gene assay showed that the -799A allele had significantly higher promoter activity than the -799T allele. Multiple regression analysis revealed that only the rs2248690 SNP was an independent contributor to serum AHAG concentration. The rs2248690 SNP in the promoter region of the AHSG gene might affect the AHSG gene transcription.

Association of AHSG Gene Polymorphisms and Aortic Stiffness in Peritoneal Dialysis Patients

Background/Aims: Fetuin-A is a negative acute-phase reactant and extraosseous calcification inhibitor. Decreased serum concentration of fetuin-A is independently related to all-cause and cardiovascular mortality in dialysis patients. Our aim is to investigate the association between the genetic polymorphism of α₂-Heremans-Schmid-glycoprotein (AHSG) encoding fetuin-A and its serum concentration, vascular calcification, and aortic stiffness in peritoneal dialysis (PD) patients. Method: A total of six single nucleotide polymorphisms (SNPs) in the AHSG gene were genotyped and evaluated for association with serum fetuin-A level, quantitative measures of vascular calcification and aortic stiffness represented by heart-to-femoral pulse wave velocity (hfPWV). Results: Five SNPs in the AHSG gene were nominally associated with the serum fetuin-A level in our PD patients. In haplotype analyses, there were haplotypes positively (H1; AGCA, H2; CC) and inversely (H1; TTCG, H2; TT) related with the serum fetuin-A level. The serum fetuin-A level inversely and independently correlated with hfPWV. Moreover, the serum fetuin-A concentration was a determinant for the simple vascular calcification score (SVCS), which subsequently was associated with hfPWV. Conclusions: Our study showed an association between AHSG polymorphism and its serum concentration, and also revealed an association of the serum fetuin-A level with SVCS and aortic stiffness in PD patients.

Serum Fetuin-A is an Independent Marker of Insulin Resistance in Japanese Men

Fetuin-A, also known as alpha2-Heremans Schmid glycoprotein, is an abundant plasma protein synthesized predominantly in the liver. Fetuin-A inhibits insulin receptor autophosphorylation, which is mediated by its intrinsic tyrosine kinase activity. In this study, we examined the association between the serum fetuin-A level and insulin resistance in Japanese men. We recruited 300 unrelated Japanese men without known chronic diseases, such as diabetes mellitus, or a history of regular drug use, and who underwent health examinations. From a 75-g oral glucose tolerance test, the study population included 194 individuals with normal glucose tolerance, 91 with impaired glucose tolerance and/or impaired fasting glucose, and 15 with diabetes mellitus. Serum fetuin-A concentrations were measured using an ELISA kit. Serum fetuin-A concentrations were positively correlated with fasting insulin levels (r = 0.269, p<0.001), HOMA-IR (r = 0.274, p<0.001) and LDL-cholesterol (r = 0.172, p<0.01), and negatively correlated with HDL-cholesterol concentrations (r = -0.191, p<0.001). Fetuin-A concentrations were also positively correlated with serum leptin (r = 0.150, p<0.01) and negatively with adiponectin concentrations (r = -0.208, p<0.001). Stepwise regression analyses confirmed that the fetuin-A concentration was independently associated with the fasting insulin level and HOMA-IR, as were body mass index, triglyceride, LDL-cholesterol, leptin and adiponectin concentrations. Our data suggest that increased serum fetuin-A levels constitute an independent marker of insulin resistance and an atherogenic lipid profile in Japanese men.

High Glucose Induces Transactivation of the .ALPHA.2-HS Glycoprotein Gene Through the ERK1/2 Signaling Pathway

Alpha2-Heremans Schmid glycoprotein (AHSG), also known as fetuin-A, is secreted from the liver and inhibits tyrosine kinase activity of the insulin receptor. Hyperglycemia in type 2 diabetes is not only a secondary manifestation of insulin resistance, but could also be responsible for directly inducing insulin resistance in target tissues. In this study, we examined the effect of high glucose (HG) on AHSG gene transcription in the human hepatoma cell line HepG2. AHSG transcriptional activity and protein expression were evaluated using reporter gene assays and Western blot analysis, respectively. D-glucose, but not L-glucose or mannitol, dose-dependently enhanced AHSG promoter activity. HG (25 mM) also increased AHSG protein expression. No protein kinase C inhibitors (bisindolylmaleimide, Ro-31-8220), an inhibitor of hexosamine biosynthesis pathway (6-diazo-5-oxo-L-norleucine), or a superoxide radical scavenger (tempol) affected HG-induced transactivation. MAPK/ERK kinase inhibitors (PD98059, U0126), but not the JNK inhibitor (SP600125) or p38 inhibitor (SB203580), significantly inhibited promoter activation by HG. Our data suggest that HG enhances AHSG transcription through activation of the ERK1/2 signaling pathway. Increased AHSG expression in the liver may be a cause of glucose toxicity in the diabetic state.

Abstract 6145: Low Fetuin-A Concentrations Predict the Progression of Aortic Valve Calcification in Non-Dialyzed Patients

Human fetuin-A (alpha 2 -Heremans Schmid glycoprotein) has been identified as the most potent circulating inhibitor of vascular and soft-tissue calcification. We aimed to investigate the relationship between the serum fetuin-A level and the progression of aortic valve calcification (AVC) assessed by retrospectively ECG-gated Multislice Spiral Computed Tomography (MSCT) in patients with calcific aortic valve disease. A prospective study in 77 non-dialyzed patients (mean age 70 ± 8 years) with echocardiographically proven aortic valve disease was performed. In all patients serum fetuin-A levels were measured by nephelometry (BNII, Dade Behring Holding, Liederbach, Germany) using a polyclonal rabbit anti-human antibody against fetuin-A. For quantification of AVC all patients underwent 16-slice MSCT (Sensation 16, Siemens, Forchheim, Germany with scan parameters as follows: 420ms tube rotation time, 12× 0.75mm collimation, tube voltage 120KV). After a mean follow-up of 12.6 ± 1.4 months a second non-enhanced MSCT examination for quantification of AVC was performed. Images were reconstructed at 60% of the RR interval. AVC was assessed using Agatston AVC score. In multifactorial analysis of covariance including fetuin-A levels, baseline AVC score, the covariables sex, age, body mass index, C-reactive protein, glomerular filtration rate, serum lipids, diabetes, smoking status and hypertension, only fetuin-A levels revealed a significant effect on the progression of AVC (p&lt;0.001). Post-hoc analysis demonstrated that patients with baseline fetuin-A levels lower than the median of the cohort (0.72g/l) showed a significantly higher increase of AVC scores (34.6 ± 31.4%, n=39) than patients with fetuin-A levels larger than the median (10.0 ± 11.2%, p&lt;0.001) despite comparable baseline AVC scores. Vice versa, patients with progressive AVC &gt; 10% (n=48, 62%) had lower fetuin-A serum levels at baseline than non-progressors (n=29, 38%; 0.66±0.13g/L versus 0.82±0.11 g/L, p&lt;0.001). The present study suggests that low fetuin-A serum levels indicating systemic calcification inhibitor deficiency were associated with increased progression of AVC independently of the renal function.

Is Fetuin-A/α2-Heremans-Schmid Glycoprotein Associated with the Metabolic Syndrome in Patients with Chronic Kidney Disease?

Introduction: Components of the metabolic syndrome are highly prevalent in chronic kidney disease (CKD) patients – some of which paradoxically appear to predict an improved outcome in this population. We hypothesized that the circulating calcification inhibitor fetuin-A/AHSG, which is also a natural inhibitor of the tyrosine kinase insulin receptor, could be one factor explaining the association between increased fat mass and a survival advantage in CKD and thus conducted an explorational study to provide preliminary data to support further research into this hypothesis. Patients and Methods: In a cross-sectional study, we evaluated 198 CKD stage 5 patients (GFR 6.8 ± 0.2 ml/min; 62% males, mean age 52 ± 1 years) close to the start of renal replacement therapy. We studied circulating AHSG (ELISA) and two common functional AHSG gene polymorphisms (at amino acids Thr248Met (C-T) and Thr256Ser (C-G) using Pyrosequencing®) and related these to multiple components of the metabolic syndrome. Results: Median circulating AHSG was lower (p < 0.01) in type-2 (0.22 g/l) and type-1 (0.16 g/l) diabetics as compared to non-diabetic CKD-5 patients (0.24 g/l). AHSG correlated with both total and truncal fat mass in type-2 diabetics (rho 0.37 and 0.39; p < 0.001, respectively), but not in type-1 diabetics or non-diabetics. Both SNPs significantly influenced circulating levels of AHSG, and were also associated with significant differences in serum triglycerides and HDL cholesterol. Furthermore, there were significant differences in the prevalence of metabolic syndrome criteria between the AHSG Thr256Ser (C-G) genotype groups, with a more atherogenic lipid profile in AHSG high producers (Thr/Thr homozygotes). In multivariate analysis, the association between circulating AHSG and fat mass remained significant also after adjustment for age, gender, inflammation (CRP >10 mg/l), and AHSG genotype. Conclusions: The present, explorational, study supports further, mechanistic, studies into a physiological link between AHSG and body fat mass in patients with CKD. As we observed an association between higher fat mass and elevated AHSG levels, these preliminary results may form the basis of further study to establish if the observed associations may be one reason why obesity has been reported to constitute a survival advantage in CKD.

A promoter polymorphism of the α2-HS glycoprotein gene is associated with its transcriptional activity

α2-Heremans Schmid glycoprotein (AHSG), also designated fetuin-A, is an abundant plasma protein that is expressed in hepatocytes. AHSG/fetuin-A has diverse biological functions including regulation of calcium homeostasis and inhibition of insulin receptor tyrosine kinase activity. The aim of this study was to detect single nucleotide polymorphisms (SNPs) of the AHSG gene that can be involved in regulation of AHSG/fetuin-A expression. By a cycle sequencing method, two common SNPs in the promoter region of AHSG gene, −799 A/T (rs2248690, dbSNP ID) and −425G/T (rs2077119), were identified. A reporter gene assay using HepG2 cells showed that the −799A allele had significantly higher promoter activity compared with the −799T allele. The overexpression of c-Fos/c-Jun significantly repressed transcriptional activity and a gel shift assay showed that the −799T DNA fragment had a greater affinity for transcription factor AP-1 than the −799A. In 40 unrelated healthy subjects, serum AHSG/fetuin-A levels increased with the following order of genotypes: −799TT < −799AT < −799AA (mean ± S.E.M.; 222.1 ± 11.0, 291.8 ± 8.1, and 349.0 ± 13.0 μg/ml, respectively, P < 0.001). In conclusion, SNP rs2248690 in the promoter region of the AHSG gene affects the AHSG gene transcription, possibly by producing different association with AP-1.

Gene Polymorphisms and Serum Alpha-2-Heremans-Schmid Levels in Italian Haemodialysis Patients

Background: Vascular calcification (VC) and accelerated atherosclerosis are major causes of cardiovascular (CV) morbidity and mortality in haemodialysis (HD) patients. Inhibitory proteins are associated with reduced VC and may play a key role in preventing CV in chronic kidney disease (CKD) patients. Fetuin-A, also known as α₂-Heremans-Schmid glycoprotein (AHSG), is a circulating plasma protein with inhibitory effects on VC that has been associated with inflammation and CV mortality in HD patients. In the present study, we investigated the associations between serum fetuin-A levels and its gene (AHSG) polymorphisms in an Italian HD population. Methods: Ninety-six patients on stable chronic HD treatment and 57 healthy controls were genotyped for the common polymorphisms on the AHSG (T256S). In addition, serum fetuin-A levels were tested. Results: In this study, serum fetuin-A levels were lower in HD patients (0.35 ± 0.11 g/l) compared with healthy controls (0.62 ± 0.31 g/l, p < 0.05). In both HD patients and the control group, the distribution of the AHSG gene did not show significant association between low serum fetuin-A levels and the Ser/Ser genotype, known to be associated with a higher CV mortality risk in the HD population. Moreover, the distribution of AHSG gene polymorphisms in HD patients and in healthy controls was similar. Conclusions: In contrast with previous reports, this study suggests that CKD patients on HD treatment have a similar polymorphism distribution of the AHSG gene compared with the normal population and that the reduction in serum fetuin-A levels in Italian HD patients is not associated with an alteration in the distribution of AHSG T256S polymorphisms.

Calcified coronary artery disease and serum markers

Severity of coronary artery calcification is closely related to atherosclerotic plaque burden and cardiac event rate. Recent data have suggested that vascular calcification is an actively regulated process similar to the bone formation, and that bone-related factors may be involved in the development of vascular calcification. Non-invasive prediction of calcified coronary artery disease is important using serum bone-related markers. Among them, we focus on matrix Gla protein, osteoprotegerin and fetuin-A as such candidates in this review.

Association of high alpha 2-Heremans–Schmid glycoprotein/fetuin concentration in serum and intima-media thickness in patients with atherosclerotic vascular disease and low bone mass

Objective Alpha 2-Heremans–Schmid glycoprotein (AHSG; fetuin), a member of the cystatin superfamily of cysteine protease inhibitors involved in vascular pathology and bone metabolism, has been reported to be reduced in patients with atherosclerosis and medial calcification related to end stage renal disease or dialysis. No data on fetuin in patients with peripheral artery disease associated with low bone mass and normal renal function are available in the literature. In the present study we evaluated serum fetuin concentrations, bone mass, and markers of bone turnover in patients with atherosclerosis of peripheral vessels and normal kidney function. Patients and methods Ninety consecutive patients with evidence of atherosclerotic plaques at the common carotid or femoral artery were studied. Severity grade of disease was documented by ultrasound measurement of intima-media thickness (IMT). Fasting serum levels of fetuin were measured by sandwich enzyme immunoassay. Main results The mean patient serum concentration of fetuin was 57.68 ± 13.6 ng/ml, significantly higher than that of control subjects (41.6 ± 7.6 ng/ml; p < 0.001). The mean serum concentration of bone-specific alkaline phosphatase (BAP) were 8.4 ± 2.3 μg/l, significantly lower than controls (13.6 ± 1.6 μg/l; p < 0.001). Fetuin was correlated with IMT ( r = 0.8530; p < 0.0001) and inversely correlated with BAP ( r = −0.5503; p < 0.0001). Patients had a vertebral and femoral bone mass significantly lower than controls. Conclusion This study documented for the first time that, in patients with atherosclerosis of peripheral vessels, serum fetuin levels were higher than in healthy subjects, and correlated with the severity of disease; further studies are required to analyse the role of AHSG as an independent predictor of atherosclerotic disease and low bone mass in patients with normal renal function.

Suppressive effect of alpha2 Heremans-Schmid glycoprotein on in vitro calcification of osteogenesis

alpha(2) Heremans-Schmid glycoprotein (alpha(2)HS glycoprotein) is predominantly found in bone. To date, we have investigated plasma alpha(2)HS levels in immature babies and neonates as well as the histological distribution in various neonatal tissues in order to clarify its physiological significance. In an effort to understand the physiological function of alpha(2)HS glycoprotein in bones, we studied the effects of alpha(2)HS glycoprotein in cultured osteogenesis model using rat marrow cells. We added different concentrations of alpha(2)HS glycoprotein to cultured marrow cells, including osteoblasts in the presence of dexamethasone, in an attempt to elucidate the effects of alpha(2)HS glycoprotein on osteoblast growth and bone calcification in vitro. The results showed that total DNA content was significantly increased with 0.2-20 nM (f.c.) alpha(2)HS glycoprotein, but was neither suppressed nor increased with 200 nM (f.c.) alpha(2)HS glycoprotein. Although ALP activity increased with 0.2 or 2 nM (f.c.) alpha(2)HS glycoprotein, it decreased with 20 or 200 nM (f.c.) alpha(2)HS glycoprotein. While 0.2 nM (f.c.) alpha(2)HS glycoprotein had no effect on calcium or osteocalcin content, 2 nM (f.c.) alpha(2)HS glycoprotein decreased both calcium content and osteocalcin content by about half, and no calcium or osteocalcin was observed with 20 or 200 nM (f.c.). Calcium staining of cultured marrow cells revealed that the number of stained cell tubercles decreased in a concentration-dependent manner. These findings suggest that alpha(2)HS glycoprotein regulates the growth of osteoblasts and acts as an inhibitory factor in the regulation of bone calcification.

Polymorphism of the AHSG gene is associated with increased adipocyte β2-adrenoceptor function

The alpha(2) Heremans-Schmid glycoprotein (AHSG) gene is implicated in the regulation of body fat and insulin sensitivity. The Met/Met genotype of the common single-nucleotide polymorphism (SNP), rs4917, in the AHSG gene has been shown to be associated with reduced plasma levels as well as lower body fat. Here, we studied the association of this variation with subcutaneous adipocyte lipolysis. Ninety-three obese and nonobese healthy men were genotyped for Thr230Met, and subcutaneous adipose tissue biopsies were analyzed for lipolysis characteristics. The Met/Met genotype was associated with a marked increase of 1.5 log units in the lipolytic sensitivity to the beta2-adrenoceptor agonist terbutaline (P=0.0008) as compared with the Thr/Thr and Thr/Met genotypes. This corresponds to an approximately 35-fold increase in beta2-adrenoceptor function. The genotype effect was independent of body mass index and waist circumference. In contrast, lipolytic sensitivity to both the beta1-adrenoceptor agonist dobutamine (P=0.25) and the alpha2A-adrenoceptor agonist clonidine (P=0.54) was unaffected by the Thr230Met variation. Moreover, no difference in either maximal stimulation or inhibition of lipolysis was found between genotypes. We conclude that a common variation (Thr230Met) in the AHSG gene is associated with a marked increase in beta2-adrenoceptor sensitivity in subcutaneous fat cells, which may be of importance in body weight regulation.

A Synonymous Coding Polymorphism in the α2-Heremans-Schmid Glycoprotein Gene Is Associated With Type 2 Diabetes in French Caucasians

alpha2-Heremans-Schmid glycoprotein (AHSG) is an abundant plasma protein synthesized predominantly in the liver. The AHSG gene, consisting of seven exons and spanning 8.2 kb of genomic DNA, is located at chromosome 3q27, a susceptibility locus for type 2 diabetes and the metabolic syndrome. AHSG is a natural inhibitor of the insulin receptor tyrosine kinase, and AHSG-null mice exhibit significantly enhanced insulin sensitivity. These observations suggested that the AHSG gene is a strong positional and biological candidate for type 2 diabetes susceptibility. Direct sequencing of the AHSG promoter region and exons identified nine common single nucleotide polymorphisms (SNPs) with a minor allele frequency > or =5%. We carried out a detailed genetic association study of the contribution of these common AHSG SNPs to genetic susceptibility of type 2 diabetes in French Caucasians. The major allele of a synonymous coding SNP in exon 7 (rs1071592) presented significant evidence of association with type 2 diabetes (P = 0.008, odds ratio 1.27 [95% CI 1.06-1.52]). Two other SNPs (rs2248690 and rs4918) in strong linkage disequilibrium with rs1071592 showed evidence approaching significance. A haplotype carrying the minor allele of SNP rs1071592 was protective against type 2 diabetes (P = 0.014). However, our analyses indicated that rs1071592 is not associated with the evidence for linkage of type 2 diabetes to 3q27.

Genetic association of alpha2-Heremans–Schmid glycoprotein polymorphism with late-onset Alzheimer's disease in Italians

Alpha2-Heremans–Schmid glycoprotein (AHSG), also known as fetuin-A, is a highly glycosylated protein which has been recently reported to be decreased in the cerebrospinal fluid of patients with Alzheimer's disease. AHSG is genetically polymorphic and two common alleles, AHSG*1 and AHSG*2, have been described. The purpose of this study was to investigate the distribution of AHSG gene polymorphism in 235 Caucasian Italian patients with late-onset Alzheimer's disease (LOAD) and 235 age- and gender-matched healthy controls. In patients with LOAD, the genotype distribution was 184 AHSG 1*1, 44 AHSG 1*2, 7 AHSG 2*2, and was significantly different from that observed in the 235 control subjects (117 AHSG 1*1, 103 AHSG 1*2, 15 AHSG 2*2) ( χ 2 = 41.50, P < 0.0001). After allowance for age, gender and APOE ɛ4 status, multivariate logistic regression analysis revealed that the adjusted odds ratio for the development of LOAD in AHSG 1*1 homozygotes was 3.90 (95% CI: 2.58–5.90, P < 0.0001). These results suggest that the AHSG gene polymorphism may be associated with LOAD in Italians. Additional studies are warranted to examine the biological relevance of AHSG in the pathophysiology of neurodegenerative disorders.

Low fetuin-A levels are associated with cardiovascular death: Impact of variations in the gene encoding fetuin

Vascular calcification is common among end-stage renal disease (ESRD) patients and a central characteristic of the atherosclerotic cardiovascular disease observed in dialysis patients. Fetuin-A, a circulating calcium-regulatory glycoprotein that inhibits vascular calcification, is associated with inflammation and outcome in dialysis patients. In the present study, we evaluated the association between fetuin-A, clinical phenotype, and outcome, as well as the impact of fetuin gene (AHSG) polymorphisms on the protein product and outcome. In a cohort of 258 (161 males) ESRD patients starting renal replacement therapy [glomerular filtration rate (GFR) 6.8 +/- 0.2 mL/min] aged 52 +/- 1 years the following parameters were studied: presence of malnutrition (subjective global assessment), comorbidity [diabetes mellitus and clinical manifest cardiovascular disease (CVD)], carotid plaques (N= 101), hs-CRP, fetuin-A, S-albumin, interleukin (IL)-6, and single nucleotide polymorphisms (SNPs) in the AHSG gene (N= 215) at amino acid positions Thr248Met (C-->T), Thr256Ser (C-->G), Asp276Asn (G-->A), and Arg317Cys (C-->T). Both all-cause (P < 0.001) and cardiovascular (P < 0.001) mortality were associated with low fetuin-A levels independently of age, smoking, diabetes, S-albumin, CVD, and inflammation (CRP > or =10 mg/L). Inflamed (0.199 vs. 0.247 g/L; P < 0.01) and malnourished (0.207 vs. 0.262 g/L; P < 0.05) patients had significantly lower median fetuin-A than noninflamed and well-nourished ESRD patients, respectively. In a logistic regression model (N= 101), fetuin-A was significantly (P < 0.05) associated with the presence of carotid plaques independently of age, CVD, diabetes, S-albumin, gender, and inflammation. Significant correlations were observed between fetuin-A and both S-albumin (Rho = 0.30; P < 0.0001) and IL-6 (Rho =-0.21; P < 0.01). Patients with the AHSG 256Ser allele had lower serum fetuin-A levels, and higher all-cause and cardiovascular mortality rate if they were inflamed. The present study shows that a low fetuin-A level is associated with malnutrition, inflammation, and atherosclerosis (carotid plaques), as well as with increased cardiovascular and all-cause mortality. Because the present study demonstrates an effect of variations in the AHSG gene on both circulating fetuin-A levels and outcome, this indicates that ESRD patients with the AHSG 256Ser allele are at risk of accelerated vascular calcification.

Associations of serum fetuin-A with malnutrition, inflammation, atherosclerosis and valvular calcification syndrome and outcome in peritoneal dialysis patients

Fetuin-A (alpha2-Heremans Schmid glycoprotein) has recently been identified as a circulating inhibitor of calcification and is regulated as a negative acute phase protein. However, its relationships with cardiac valvular calcification and atherosclerosis and outcome have not been evaluated in peritoneal dialysis (PD) patients. We performed a prospective follow-up study in 238 PD patients with echocardiography done at baseline to detect cardiac valvular calcification and biochemical analysis performed for serum fetuin-A, albumin and C-reactive protein (CRP). Baseline serum fetuin-A concentration was (mean+/-SD) 0.309+/-0.068 g/l (normal range 0.4-0.95). Across the three tertiles of increasing serum fetuin-A, a significant trend effect was observed for age (P = 0.023), diabetes (P = 0.008), background atherosclerotic vascular disease (P = 0.010), cardiac valvular calcification (P = 0.002), serum albumin (P<0.001), subjective global assessment (P = 0.005) and CRP (P<0.001). Adjusting for CRP and calcium x phosphorus product, every 0.01 g/l increase in serum fetuin-A remained independently associated with a 6% decrease in the risk of valvular calcification (95% confidence intervals, 0.90-0.99; P = 0.028). Furthermore, serum fetuin-A showed a significant decrease across the four groups of patients with increasing components of the malnutrition, inflammation, atherosclerosis/calcification (MIAC) syndrome (P<0.001) and was the lowest among patients with all components of the MIAC syndrome (0.263+/-0.055 g/l) and highest among those who do not have the MIAC syndrome at all (0.338+/-0.063 g/l). Lower serum fetuin-A was associated with greater all-cause mortality (P = 0.0011) and fatal and non-fatal cardiovascular events (P = 0.0017), but its significance was lost when atherosclerotic vascular disease, valvular calcification, inflammation and malnutrition were included in the model. Serum fetuin-A showed important associations with valvular calcification, atherosclerosis, malnutrition and inflammation, and was linked to mortality and cardiovascular events in PD patients via its close relationships with the MIAC syndrome.

AHSG gene variant is associated with leanness among Swedish men

Alpha(2) Heremans-Schmid glycoprotein (AHSG) is a plasma protein inhibiting the activity of the insulin receptor tyrosine kinase. Ahsg knock-out mice have increased insulin sensitivity and are resistant to diet-induced obesity. We hypothesized that functional variants of the AHSG gene segregating in the human population would reflect variation in body mass index (BMI). We genotyped 356 overweight or obese (BMI: 37.2 [25.0-66.5] kg/m(2)) and 148 lean (BMI: 23.7 [23.4-24.9] kg/m(2)) otherwise healthy Swedish men for three non-synonymous single-nucleotide polymorphisms (SNPs) within exon 6 (rs4917) and exon 7 (rs4918 and Arg299Cys) and one SNP in intron 1 (rs2593813) of the AHSG gene. The G/G genotype for rs2593813 was more common among lean than among obese and overweight individuals (odds ratio = 2.01, P = 0.009), whereas rs2593813 was in strong linkage disequilibrium (|D'| > or = 0.97) with rs4917 and rs4918. Homozygosity for the rs2593813:G-rs4917:Met-rs4918:Ser haplotype conferred an increased risk for leanness (odds ratio=1.90, P = 0.027). rs4917:Met and rs4918:Ser have previously been associated with lower AHSG protein level. A common variant of AHSG, previously associated with a lower AHSG protein level, is thus more common among lean than obese and overweight men, supporting the results from Ahsg knock-out mice, namely, that AHSG modulates body mass.