Family-Based Association Analysis Confirms the Role of the Chromosome 9q21.32 Locus in the Susceptibility of Diabetic Nephropathy

A genome-wide association scan of type 1 diabetic patients from the GoKinD collections previously identified four novel diabetic nephropathy susceptibility loci that have subsequently been shown to be associated with diabetic nephropathy in unrelated patients with type 2 diabetes. To expand these findings, we examined whether single nucleotide polymorphisms (SNPs) at these susceptibility loci were associated with diabetic nephropathy in patients from the Joslin Study of Genetics of Nephropathy in Type 2 Diabetes Family Collection. Six SNPs across the four loci identified in the GoKinD collections and 7 haplotype tagging SNPs, were genotyped in 66 extended families of European ancestry. Pedigrees from this collection contained an average of 18.5 members, including 2 to 14 members with type 2 diabetes. Among diabetic family members, the 9q21.32 locus approached statistical significance with advanced diabetic nephropathy (P = 0.037 [adjusted P = 0.222]). When we expanded our definition of diabetic nephropathy to include individuals with high microalbuminuria, the strength of this association improved significantly (P = 1.42×10−3 [adjusted P = 0.009]). This same locus also trended toward statistical significance with variation in urinary albumin excretion in family members with type 2 diabetes (P = 0.032 [adjusted P = 0.192]) and in analyses expanded to include all relatives (P = 0.019 [adjusted P = 0.114]). These data increase support that SNPs identified in the GoKinD collections on chromosome 9q21.32 are true diabetic nephropathy susceptibility loci

Review of the Constellation Level II Safety, Reliability, and Quality Assurance (SR&QA) Requirements Documents during Participation in the Constellation Level II SR&QA Forum

At the request of the Exploration Systems Mission Directorate (ESMD) and the Constellation Program (CxP) Safety, Reliability; and Quality Assurance (SR&QA) Requirements Director, the NASA Engineering and Safety Center (NESC) participated in the Cx SR&QA Requirements forum. The Requirements Forum was held June 24-26; 2008, at GRC's Plum Brook Facility. The forums purpose was to gather all stakeholders into a focused meeting to help complete the process of refining the CxP to refine its Level II SR&QA requirements or defining project-specific requirements tailoring. Element prime contractors had raised specific questions about the wording and intent of many requirements in areas they felt were driving costs without adding commensurate value. NESC was asked to provide an independent and thorough review of requirements that contractors believed were driving Program costs, by active participation in the forum. This document contains information from the forum

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 P1105. The strongest association was at the FRMD3 (4.1 protein ezrin, radixin, moesin [FERM] domain containing 3) locus (odds ratio [OR]1.45, P5.0107). A strong association was also identified at the CARS (cysteinyl-tRNA synthetase) locus (OR 1.36, P3.1106). Associations between both loci and time to onset of diabetic nephropathy were supported in the DCCT/EDIC study (hazard ratio [HR]1.33, P0.02, and HR1.32, P 0.01, respectively). We demonstrated expression 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

Association of Coding Variants in Hydroxysteroid 17-beta Dehydrogenase 14 (HSD17B14) with Reduced Progression to End Stage Kidney Disease in Type 1 Diabetes

Background Rare variants ingenecodingregions likely have agreater impactondisease-relatedphenotypes than common variants through disruption of their encoded protein. We searched for rare variants associated with onset of ESKD in individuals with type 1 diabetes at advanced kidney disease stage. Methods Gene-basedexome array analyses of15,449genes infivelarge incidence cohortsof individualswith type 1diabetes andproteinuriawere analyzedfor survival time toESKD, testing the top gene in a sixth cohort (n52372/1115 events all cohorts) and replicating in two retrospective case-control studies (n51072 cases, 752 controls). Deep resequencing of the top associated gene in five cohorts confirmed the findings. We performed immunohistochemistry and gene expression experiments in human control and diseased cells, and in mouse ischemia reperfusion and aristolochic acid nephropathy models. Results Protein coding variants in the hydroxysteroid 17- b dehydrogenase 14 gene (HSD17B14), predicted to affect protein structure, had a net protective effect against development of ESKD at exome-wide significance (n54196; P value53.331027). The HSD17B14 gene and encoded enzyme were robustly expressed in healthy human kidney, maximally in proximal tubular cells. Paradoxically, gene and protein expression were attenuated in human diabetic proximal tubules and in mouse kidney injury models. Expressed HSD17B14 gene and protein levels remained low without recovery after 21 days in a murine ischemic reperfusion injury model. Decreased gene expression was found in other CKD-associated renal pathologies. Conclusions HSD17B14 gene ismechanistically involved in diabetic kidney disease. The encoded sex steroid enzyme is a druggable target, potentially opening a new avenue for therapeutic development.Peer reviewe

Genome-Wide Association and Trans-ethnic Meta-Analysis for Advanced Diabetic Kidney Disease: Family Investigation of Nephropathy and Diabetes (FIND)

Diabetic kidney disease (DKD) is the most common etiology of chronic kidney disease (CKD) in the industrialized world and accounts for much of the excess mortality in patients with diabetes mellitus. Approximately 45% of U.S. patients with incident end-stage kidney disease (ESKD) have DKD. Independent of glycemic control, DKD aggregates in families and has higher incidence rates in African, Mexican, and American Indian ancestral groups relative to European populations. The Family Investigation of Nephropathy and Diabetes (FIND) performed a genome-wide association study (GWAS) contrasting 6,197 unrelated individuals with advanced DKD with healthy and diabetic individuals lacking nephropathy of European American, African American, Mexican American, or American Indian ancestry. A large-scale replication and trans-ethnic meta-analysis included 7,539 additional European American, African American and American Indian DKD cases and non-nephropathy controls. Within ethnic group meta-analysis of discovery GWAS and replication set results identified genome-wide significant evidence for association between DKD and rs12523822 on chromosome 6q25.2 in American Indians (P = 5.74x10-9). The strongest signal of association in the trans-ethnic meta-analysis was with a SNP in strong linkage disequilibrium with rs12523822 (rs955333; P = 1.31x10-8), with directionally consistent results across ethnic groups. These 6q25.2 SNPs are located between the SCAF8 and CNKSR3 genes, a region with DKD relevant changes in gene expression and an eQTL with IPCEF1, a gene co-translated with CNKSR3. Several other SNPs demonstrated suggestive evidence of association with DKD, within and across populations. These data identify a novel DKD susceptibility locus with consistent directions of effect across diverse ancestral groups and provide insight into the genetic architecture of DKD

Variations in Risk of End-Stage Renal Disease and Risk of Mortality in an International Study of Patients With Type 1 Diabetes and Advanced Nephropathy

OBJECTIVE Patients with type 1 diabetes and diabetic nephropathy are targets for intervention to reduce high risk of end-stage renal disease (ESRD) and deaths. This study compares risks of these outcomes in four international cohorts. RESEARCH DESIGN AND METHODS In the 1990s and early 2000s, Caucasian patients with type 1 diabetes with persistent macroalbuminuria in chronic kidney disease stages 1-3 were identified in the Joslin Clinic (U. S., 432), Finnish Diabetic Nephropathy Study (FinnDiane) (Finland, 486), Steno Diabetes Center Copenhagen (Denmark, 368), and INSERM (France, 232) and were followed for 3-18 years with annual creatinine measurements to ascertain ESRD and deaths unrelated to ESRD. RESULTS During 15,685 patient-years, 505 ESRD cases (rate 32/1,000 patient-years) and 228 deaths unrelated to ESRD (rate 14/1,000 patient-years) occurred. Risk of ESRD was associated with male sex; younger age; lower estimated glomerular filtration rate (eGFR); higher albumin/creatinine ratio, HbA1c, and systolic blood pressure; and smoking. Risk of death unrelated to ESRD was associated with older age, smoking, and higher baseline eGFR. In adjusted analysis, ESRD risk was highest in Joslin versus reference FinnDiane (hazard ratio [HR] 1.44, P = 0.003) and lowest in Steno (HR 0.54, P <0.001). Differences in eGFR slopes paralleled risk of ESRD. Mortality unrelated to ESRD was lowest in Joslin (HR 0.68, P = 0.003 vs. the other cohorts). Competing risk did not explain international differences in the outcomes. CONCLUSIONS Despite almost universal renoprotective treatment, progression to ESRD and mortality in patients with type 1 diabetes with advanced nephropathy are still very high and differ among countries. Finding causes of these differences may help reduce risk of these outcomes.Peer reviewe

Family-based association results between DN-associated SNPs and ESRD among diabetic family members.

#<p>Families  =  number of nuclear families informative for the FBAT analysis.</p><p>S-E(S)  =  observed minus the expected transmission for each allele.</p><p>Var(S)  =  variance of the observed transmission for each allele.</p><p>Z score: positive values indicate risk alleles (i.e., increased transmission to affected individuals), negative values indicate protective alleles (i.e., reduced transmission to affected individuals).</p>*<p>Risk allele reported in <i>Pezzolesi et al</i>. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060301#pone.0060301-Pezzolesi2" target="_blank">[18]</a></p

Family-based haplotype analysis between chromosome 9q21.32^* haplotypes and logACR among diabetic family members.

*<p>9q21.32 haplotypes: rs1888747, rs1929547, and rs10868025.</p><p>Haplotypes with estimated frequencies ≥0.01 are provided and were used to calculate global <i>P</i>-values.</p>#<p>Families  =  number of nuclear families informative for the HBAT analysis; a minimum of 5 informative families for each haplotype was required to compute global tests.</p><p>S-E(S)  =  observed minus the expected transmission for each haplotype.</p><p>Var(S)  =  variance of the observed transmission for each haplotype.</p><p>Z score: positive values indicate risk haplotypes, negative values indicate protective haplotypes.</p><p>Associations achieving nominal significance (<i>P</i>-value<0.05) are indicated in bold.</p

Family-based association results between DN-associated SNPs and nephropathy (normoalbuminuria vs. high microalbuminuria/proteinuria/ESRD) among diabetic family members.

#<p>Families  =  number of nuclear families informative for the FBAT analysis.</p><p>S-E(S)  =  observed minus the expected transmission for each allele.</p><p>Var(S)  =  variance of the observed transmission for each allele.</p><p>Z score: positive values indicate risk alleles (i.e., increased transmission to affected individuals), negative values indicate protective alleles (i.e., reduced transmission to affected individuals).</p><p>Associations achieving nominal significance (<i>P</i>-value<0.05) are indicated in bold.</p>*<p>Risk allele reported in <i>Pezzolesi et al</i>. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060301#pone.0060301-Pezzolesi2" target="_blank">[18]</a></p