Grzegorz Placha

Genome-Wide Association Scan for Diabetic Nephropathy Susceptibility Genes in Type 1 Diabetes

OBJECTIVE Despite extensive evidence for genetic susceptibility to diabetic nephropathy, the identification of susceptibility genes and their variants has had limited success. To search for genes that contribute to diabetic nephropathy, a genome-wide association scan was implemented on the Genetics of Kidneys in Diabetes collection. RESEARCH DESIGN AND METHODS We genotyped ∼360,000 single nucleotide polymorphisms (SNPs) in 820 case subjects (284 with proteinuria and 536 with end-stage renal disease) and 885 control subjects with type 1 diabetes. Confirmation of implicated SNPs was sought in 1,304 participants of the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study, a long-term, prospective investigation of the development of diabetes-associated complications. RESULTS A total of 13 SNPs located in four genomic loci were associated with diabetic nephropathy with P < 1 × 10−5. The strongest association was at the FRMD3 (4.1 protein ezrin, radixin, moesin [FERM] domain containing 3) locus (odds ratio [OR] = 1.45, P = 5.0 × 10−7). A strong association was also identified at the CARS (cysteinyl-tRNA synthetase) locus (OR = 1.36, P = 3.1 × 10−6). Associations between both loci and time to onset of diabetic nephropathy were supported in the DCCT/EDIC study (hazard ratio [HR] = 1.33, P = 0.02, and HR = 1.32, P = 0.01, respectively). We demonstratedexpression of both FRMD3 and CARS in human kidney. CONCLUSIONS We identified genetic associations for susceptibility to diabetic nephropathy at two novel candidate loci near the FRMD3 and CARS genes. Their identification implicates previously unsuspected pathways in the pathogenesis of this important late complication of type 1 diabetes.

New Polymorphism of ENPP1 (PC-1) Is Associated With Increased Risk of Type 2 Diabetes Among Obese Individuals

The K121Q polymorphism in ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is associated with type 2 diabetes and obesity. The possibility of other ENPP1 polymorphisms influencing these phenotypes has received little attention. Our aim was to examine the associations of tagging single nucleotide polymorphisms (SNPs) and haplotypes of the linkage disequilibrium (LD) block containing K121Q polymorphism with type 2 diabetes in a Polish population, controlling for any effect of obesity. We genotyped 426 type 2 diabetic case and 370 control subjects for seven SNPs in ENPP1. In the total group, neither type 2 diabetes nor obesity was significantly associated with any SNP. However, in obese subjects, two SNPs were significantly associated with type 2 diabetes: the Q allele of K121Q (odds ratio 1.6 [95% CI 1.003–2.6]) and T allele of rs997509 (4.7 [1.6–13.9]). In the LD block, four SNPs plus the K121Q polymorphism distinguished six haplotypes, three of which carried the Q allele. Interestingly, the T allele of rs997509 sufficed to distinguish a 121Q-carrying haplotype that was significantly more associated with type 2 diabetes than the other two (4.2 [1.3–13.5]). These other two 121Q-carrying haplotypes were not associated with type 2 diabetes. In conclusion, we found a new SNP, rs997509, in intron 1 that is strongly associated with risk of type 2 diabetes in obese individuals. The molecular mechanisms underlying this association are unknown.

A Genome-Wide Linkage Scan for Genes Controlling Variation in Renal Function Estimated by Serum Cystatin C Levels in Extended Families With Type 2 Diabetes

We performed a variance components linkage analysis of renal function, measured as glomerular filtration rate (GFR), in 63 extended families with multiple members with type 2 diabetes. GFR was estimated from serum concentrations of cystatin C and creatinine in 406 diabetic and 428 nondiabetic relatives. Results for cystatin C were summarized because they are superior to creatinine results. GFR aggregates in families with significant heritability (h2) in diabetic (h2 = 0.45, P < 1 × 10−5) and nondiabetic (h2 = 0.36, P < 1 × 10−3) relatives. Genetic correlation (rG = 0.35) between the GFR of diabetic and nondiabetic relatives was less than one (P = 0.01), suggesting that genes controlling GFR variation in these groups are different. Linkage results supported this interpretation. In diabetic relatives, linkage was strong on chromosome 2q (logarithm of odds [LOD] = 4.1) and suggestive on 10q (LOD = 3.1) and 18p (LOD = 2.2). In nondiabetic relatives, linkage was suggestive on 3q (LOD = 2.2) and 11p (LOD = 2.1). When diabetic and nondiabetic relatives were combined, strong evidence for linkage was found only on 7p (LOD = 4.0). In conclusion, partially distinct sets of genes control GFR variation in relatives with and without diabetes on chromosome 2q, possibly on 10q and 18p in the former, and on 7p in both. None of these genes overlaps with genes controlling variation in urinary albumin excretion.

Exclusion of polymorphisms in carnosinase genes (CNDP1 and CNDP2) as a cause of diabetic nephropathy in type 1 diabetes: results of large case-control and follow-up studies.

OBJECTIVES— Recently, an association was found between diabetic nephropathy and the D18S880 microsatellite, located in the carnosinase gene (CNDP1) on chromosome 18q. Alleles of this microsatellite encode for a variable number of leucine residues (from four to seven) in the leader peptide of the carnosinase precursor. The frequency of subjects homozygous for the five leucines was higher in control subjects than in case subjects in studies focusing on type 2 diabetic patients. To test whether this finding can be extended to type 1 diabetic patients, we carried out a comprehensive study on association between diabetic nephropathy and the D18S880 microsatellite and 21 additional SNPs that tagged the genomic region containing CNDP1 and CNDP2. RESEARCH DESIGN AND METHODS— Overall, 1,269 Caucasian patients with type 1 diabetes were included in the study, including 613 patients with normoalbuminuria and a long duration of diabetes, 445 patients with persistent proteinuria, and 211 patients with end-stage renal disease (ESRD). All patients were genotyped for selected polymorphisms, the associations with diabetic nephropathy were tested by a χ2 test, and odds ratios were calculated. RESULTS— We did not find any significant association between diabetic nephropathy and any examined genetic markers. The negative findings of the case-control study were supported further by negative findings obtained from the 6-year follow-up study of 445 patients with persistent proteinuria, during which 135 patients developed ESRD. CONCLUSIONS— Our large, comprehensive study did not find an association between the D18S880 microsatellite or any other polymorphisms in the CNDP2–CNDP1 genomic region and susceptibility for diabetic nephropathy in type 1 diabetes.

Common haplotypes at the adiponectin receptor 1 (ADIPOR1) locus are associated with increased risk of coronary artery disease in type 2 diabetes

Adiponectin, an adipokine facilitating insulin action, has antiatherogenic effects. This study investigated whether common polymorphisms in the adiponectin receptor 1 (ADIPOR1) gene mediating these effects influence the risk of coronary artery disease (CAD) in type 2 diabetes. Linkage disequilibrium analysis of 28 single nucleotide polymorphisms (SNPs) spanning the entire ADIPOR1 locus revealed two haplotype blocks that could be tagged by six SNPs. These six markers were typed in two populations of CAD-positive and -negative subjects with type 2 diabetes, one from Boston (n = 411) and the other from Italy (n = 533). In the Boston population, the three tags of the more 3′ block were all significantly associated with CAD (P = 0.001–0.01). A similar trend, although not significant, was found in Italian subjects. Haplotype analysis of the combined populations revealed different haplotype distributions in case and control subjects (P = 0.0002), with one common haplotype being associated in homozygotes with a greater than threefold increase in cardiovascular risk (odds ratio 3.6 [95% CI 1.8–7.2]). Some of the genotypes associated with increased cardiovascular risk were associated with 30–40% lower ADIPOR1 mRNA levels in blood mononuclear cells (n = 60) and adipose tissue biopsies (n = 28) (P = 0.001–0.014). Our findings point to genetic variability at the ADIPOR1 locus as a strong determinant of CAD susceptibility in type 2 diabetes.

A Disease Haplotype for Advanced Nephropathy in Type 2 Diabetes at the ACE Locus

Previous investigations of the ACE gene as a susceptibility factor for diabetic nephropathy have primarily focused on its insertion/deletion (Ins/Del) polymorphism. In a departure from these earlier studies, we used three tagging markers (A-5466C, T-3892C, and Ins/Del) at the ACE locus to test for disease haplotype associations. A case-control study design was used where case subjects were type 2 diabetic patients with advanced diabetic nephropathy, as indicated by the presence of proteinuria or chronic renal failure/end-stage renal disease, while control subjects were normoalbuminuric, despite >6 years of diabetes. None of the individual markers showed significant disease association when considered on their own. However, haplotype analyses revealed a near doubling in the prevalence of the A.T.D risk haplotype in case subjects (0.136) compared with control subjects (0.075) (P = 0.009), thus providing first evidence for a disease haplotype for advanced diabetic nephropathy at the ACE locus.

Exclusion of Polymorphisms in Carnosinase Genes (CNDP1 and CNDP2) as a Cause of Diabetic Nephropathy in Type 1 Diabetes

OBJECTIVES— Recently, an association was found between diabetic nephropathy and the D18S880 microsatellite, located in the carnosinase gene (CNDP1) on chromosome 18q. Alleles of this microsatellite encode for a variable number of leucine residues (from four to seven) in the leader peptide of the carnosinase precursor. The frequency of subjects homozygous for the five leucines was higher in control subjects than in case subjects in studies focusing on type 2 diabetic patients. To test whether this finding can be extended to type 1 diabetic patients, we carried out a comprehensive study on association between diabetic nephropathy and the D18S880 microsatellite and 21 additional SNPs that tagged the genomic region containing CNDP1 and CNDP2. RESEARCH DESIGN AND METHODS— Overall, 1,269 Caucasian patients with type 1 diabetes were included in the study, including 613 patients with normoalbuminuria and a long duration of diabetes, 445 patients with persistent proteinuria, and 211 patients with end-stage renal disease (ESRD). All patients were genotyped for selected polymorphisms, the associations with diabetic nephropathy were tested by a χ2 test, and odds ratios were calculated. RESULTS— We did not find any significant association between diabetic nephropathy and any examined genetic markers. The negative findings of the case-control study were supported further by negative findings obtained from the 6-year follow-up study of 445 patients with persistent proteinuria, during which 135 patients developed ESRD. CONCLUSIONS— Our large, comprehensive study did not find an association between the D18S880 microsatellite or any other polymorphisms in the CNDP2–CNDP1 genomic region and susceptibility for diabetic nephropathy in type 1 diabetes.

Liddle syndrome caused by P616R mutation of the epithelial sodium channel beta subunit

Sirs, Liddle syndrome is an autosomal dominant form of hypertension characterized by constitutively elevated renal Na reabsorption that results from deletion or missense mutation of a PPPxY motif (PY motif) in the cytoplasmatic C-terminus of either b or g subunit of the epithelial sodium channel (ENaC). Consequently, Nedd4, a protein containing ubiquitin protein ligase domain, binding to the PY ENaC motif, fails to occur, the channels are not internalized and remain activated on the cell surface instead [1]. Basic features of the aforementioned syndrome were described in a large kindred from Alabama by Grant Liddle and co-workers in 1963 and include an early onset of hypertension, diminished serum potassium levels, excessive urinary potassium excretion, suppressed plasma renin activity, and blunted aldosterone secretion rates. Blood pressure might be normalized by treatment of patients with the epithelial sodium-channel blockers amiloride or triamterene, together with a low salt diet [1, 2]. Here, we report a Czech family with Liddle syndrome in which the affected patients carry a mutation in codon 616 of the b ENaC subunit, resulting in substitution of arginine for one highly conserved proline residue. Clinical characteristics of the index case have recently been reported [3]. Briefly, an 8-year-old Caucasian boy was admitted to University Hospital in Brno for evaluation of hypertension (155/100 mmHg) and severe hypokalemia (2.4 mmol L ) in 1997. Further examination revealed suppression of plasma renin activity (0.13 nmol L 1 h ) and a low plasma concentration of aldosterone (0.06 nmol L ). Concentrations of urinary catecholamines, 17ketosteroids, 17-OH-corticosteroids, plasma cortisol, and glomerular filtration rate were all within normal range. A follow-up examination showed complete normalization of blood pressure and laboratory parameters after two weeks of treatment with amiloride. The proband’s father was first noted to be hypertensive (195/125 mmHg) at the age of 18 years during his military service. He also demonstrated hypokalemia (2.6 mmol L ) with suppression of plasma renin activity (0.38 nmol L 1 h ) and reduced plasma concentration of aldosterone (0.09 nmol L ). The proband, his father, and the unaffected, normotensive proband’s mother and sister were all invited to give blood samples for molecular studies of their ENaC subunit genes. Genomic DNA was extracted from blood leukocytes using standard techniques. The coding sequences of the C-terminal exons of b and g ENaC of the family members were amplified by polymerase chain reaction using the following primers: 50-GAGCTCACCCCAGCTCCCTG-30 and 50-CAGTCTTGGC TGCTCAGTGAG-30 (bENaC, fragment size 463 bp) and 50-TTGATGGTGTGGCTTG GCCTG-30 and 50-GATCTGTCTTCTCAAACCCTGC-30 (gENaC, fragment size 432 bp). The PCR products were sequenced bidirectionally with ABI Prism Dye Terminator Cycle Sequencing Ready Reaction Kit (Applied Biosystems) according to the manufacturers’ procedure and analyzed on the ABI PRISM 310 Genetic Analyzer (Applied Biosystems). A heterozygous C to G transversion at the second base of codon 616 bENaC was detected in the proband and his father (Fig. 1). The mutation causes substitution of proline (CCC) at position 616 by arginine (CGC). No P616R bENaC mutation has been observed in other family members (proband’s mother and sister) or in 100 unrelated subjects screened by direct DNA sequencing. Therefore, despite a lack of functional expression studies in the Xenopus ooA. Ciechanowicz ()) · A. Brodkiewicz · G. Adler Pomeranian Medical University, Department of Pathobiochemistry and Molecular Biology, ul. Powstancow Wlkp. 72, 70-111 Szczecin, Poland e-mail: aciech@sci.pam.szczecin.pl

Expression of eotaxins in the material from nasal brushing in asthma, allergic rhinitis and COPD patients

BACKGROUND Asthma and COPD are non-infectious inflammatory diseases of the respiratory tract. Allergic rhinitis can be assumed as an intermediate condition between healthy and asthmatic state. Eotaxins are important indicators of allergic reaction. They are strong chemoattractants mainly for eosinophils but also for other cells. OBJECTIVE We measured the level of eotaxin expression and inflammatory cell count in the material from nasal brushing in healthy controls and in patients with allergic rhinitis, asthma, and COPD. We studied the correlation between the eotaxin gene expression level in the material from nasal brushing and respiratory tests in asthma and COPD patients. METHODS Expression of eotaxins was measured using quantitative RT-PCR. Number of eotaxin transcript copies was evaluated using real time PCR standard curve method. RESULTS Of all eotaxins CCL24 had the highest expression in the material from nasal brushing, and its level was increased in allergic asthma. CCL11 was significantly increased in the material from nasal brushing of COPD patients. Increased levels of all three eotaxins were observed in the material from nasal brushing of patients with allergic rhinitis in season. The levels of CCL26 expression and FEV1/FVC factor were correlated negatively in the asthma group and positively in the COPD group. CONCLUSIONS Eotaxins are crucial factors of allergic, asthmatic and also COPD inflammatory reactions. Our results suggest a dual role of CCL26 - it can act as a negative regulator for neutrophils in COPD, while in asthma it may act as a chemoatractant of eosinophils and other cells into the lung.

Association of the common genetic polymorphisms and haplotypes of the chymase gene with left ventricular mass in male patients with symptomatic aortic stenosis.

We investigated the association between polymorphisms and haplotypes of the chymase 1 gene (CMA1) and the left ventricular mass index (LVM/BSA) in a large cohort of patients with aortic stenosis (AS). Additionally, the gender differences in cardiac remodeling and hypertrophy were analyzed. The genetic background may affect the myocardial response to pressure overload. In human cardiac tissue, CMA1 is involved in angiotensin II production and TGF-β activation, which are two major players in the pathogenesis of hypertrophy and fibrosis. Preoperative echocardiographic data from 648 patients with significant symptomatic AS were used. The LVM/BSA was significantly lower (p<0.0001), but relative wall thickness (RWT) was significantly higher (p = 0.0009) in the women compared with the men. The haplotypes were reconstructed using six genotyped polymorphisms: rs5248, rs4519248, rs1956932, rs17184822, rs1956923, and rs1800875. The haplotype h1.ACAGGA was associated with higher LVM/BSA (p = 9.84×10−5), and the haplotype h2.ATAGAG was associated with lower LVM/BSA (p = 0.0061) in men, and no significant differences were found in women. Two polymorphisms within the promoter region of the CMA1 gene, namely rs1800875 (p = 0.0067) and rs1956923 (p = 0.0015), influenced the value of the LVM/BSA in males. The polymorphisms and haplotypes of the CMA1 locus are associated with cardiac hypertrophy in male patients with symptomatic AS. Appropriate methods for the indexation of heart dimensions revealed substantial sex-related differences in the myocardial response to pressure overload.