African Americans have high incidence rates of end-stage renal disease (ESRD) labeled as due to hypertension. As recent studies showed strong association with idiopathic and HIV-related focal segmental glomerulosclerosis and non-muscle myosin heavy chain 9 (MYH9) gene polymorphisms in this ethnic group, we tested for MYH9 associations in a variety of kidney diseases. Fifteen MYH9 single-nucleotide polymorphisms were evaluated in 175 African Americans with chronic glomerulonephritis-associated ESRD, 696 African Americans reportedly with hypertension-associated ESRD, and 948 control subjects without kidney disease. Significant associations were detected with 14 of the 15 polymorphisms in all 871 non-diabetic patients with ESRD. In hypertension-associated ESRD cases alone, significant associations were found with 13 MYH9 polymorphisms and the previously reported E1 haplotype. Thus, hypertension-associated ESRD in African Americans is substantially related to MYH9 gene polymorphisms and this may explain the poor response to blood pressure control in those diagnosed with hypertensive nephrosclerosis. It is possible that many African Americans classified as having hypertension-associated ESRD have occult MYH9-associated segmental or global glomerulosclerosis. Our study shows that gene-environment and/or gene–gene interactions may initiate kidney disease in genetically susceptible individuals, because African Americans homozygous for MYH9 risk alleles do not universally develop kidney disease.

Juvenile loggerhead turtles (Caretta caretta) from West Atlantic nesting beaches occupy oceanic (pelagic) habitats in the eastern Atlantic and Mediterranean, whereas larger juvenile turtles occupy shallow (neritic) habitats along the continental coastline of North America. Hence the switch from oceanic to neritic stage can involve a trans-oceanic migration. Several researchers have suggested that at the end of the oceanic phase, juveniles are homing to feeding habitats in the vicinity of their natal rookery. To test the hypothesis of juvenile homing behaviour, we surveyed 10 juvenile feeding zones across the eastern USA with mitochondrial DNA control region sequences (N = 1437) and compared these samples to potential source (nesting) populations in the Atlantic Ocean and Mediterranean Sea (N = 465). The results indicated a shallow, but significant, population structure of neritic juveniles (PhiST = 0.0088, P = 0.016), and haplotype frequency differences were significantly correlated between coastal feeding populations and adjacent nesting populations (Mantel test R2 = 0.52, P = 0.001). Mixed stock analyses (using a Bayesian algorithm) indicated that juveniles occurred at elevated frequency in the vicinity of their natal rookery. Hence, all lines of evidence supported the hypothesis of juvenile homing in loggerhead turtles. While not as precise as the homing of breeding adults, this behaviour nonetheless places juvenile turtles in the vicinity of their natal nesting colonies. Some of the coastal hazards that affect declining nesting populations may also affect the next generation of turtles feeding in nearby habitats.

A genome-wide association study was performed using the Affymetrix 6.0 chip to identify genes associated with diabetic nephropathy in African Americans. Association analysis was performed adjusting for admixture in 965 type 2 diabetic African American patients with end-stage renal disease (ESRD) and in 1029 African Americans without type 2 diabetes or kidney disease as controls. The top 724 single nucleotide polymorphisms (SNPs) with evidence of association to diabetic nephropathy were then genotyped in a replication sample of an additional 709 type 2 diabetes-ESRD patients and 690 controls. SNPs with evidence of association in both the original and replication studies were tested in additional African American cohorts consisting of 1246 patients with type 2 diabetes without kidney disease and 1216 with non-diabetic ESRD to differentiate candidate loci for type 2 diabetes-ESRD, type 2 diabetes, and/or all-cause ESRD. Twenty-five SNPs were significantly associated with type 2 diabetes-ESRD in the genome-wide association and initial replication. Although genome-wide significance with type 2 diabetes was not found for any of these 25 SNPs, several genes, including RPS12, LIMK2, and SFI1 are strong candidates for diabetic nephropathy. A combined analysis of all 2890 patients with ESRD showed significant association SNPs in LIMK2 and SFI1 suggesting that they also contribute to all-cause ESRD. Thus, our results suggest that multiple loci underlie susceptibility to kidney disease in African Americans with type 2 diabetes and some may also contribute to all-cause ESRD.

Several genes that predispose to type 2 diabetes have recently been identified. In addition to the recognized and powerful effects of environmental factors, there is abundant evidence in support of genetic susceptibility to the microvascular complication of nephropathy in individuals with both type 1 and type 2 diabetes. Familial aggregation of phenotypes such as end-stage renal disease, albuminuria, and chronic kidney disease have routinely been reported in populations throughout the world, and heritability estimates for albuminuria and glomerular filtration rate demonstrate strong contributions of inherited factors. Recent genome-wide linkage scans have identified several chromosomal regions that likely contain diabetic nephropathy susceptibility genes, and association analyses have evaluated positional candidate genes under these linkage peaks. These complimentary approaches have demonstrated that polymorphisms in the carnosinase 1 gene on chromosome 18q, the adiponectin gene on 3q, and the engulfment and cell motility gene on 7p are likely associated with susceptibility to diabetic nephropathy. Additional genes that seem to be of importance in renal phenotypes include manganese superoxide dismutase and angiotensin 1-converting enzyme, with nitric oxide synthase implicated in albuminuria. This article reviews the inherited aspects of diabetic kidney disease with particular emphasis on recently implicated genes and pathways. It seems likely that the risk for diabetes-associated kidney disease is magnified by inheriting risk alleles at several susceptibility loci, in the presence of hyperglycemia.Clin J Am Soc Nephrol 2: 1306 -1316, 2007. doi: 10.2215/CJN.02560607 I t was previously thought that individuals who had diabetes and developed progressive diabetic nephropathy (DN) and/or ESRD were simply exposed to long durations of diabetes with relatively poor glycemic control. In other words, all individuals with diabetes were assumed to be at essentially equivalent risk for developing nephropathy, allowing for differences in their ambient serum glucose concentration. In support of the concept that exposure to a hyperglycemic environment led to DN (often with coexisting obesity, metabolic syndrome, hypertension, and hyperlipidemia), clinical trials have conclusively demonstrated that improving glycemic control delays and, in some cases, may prevent the subsequent development of albuminuria, DN, and macrovascular complications such as coronary artery disease (1,2). The concept that select individuals with diabetes were at differential risk for developing nephropathy on the basis of familial aggregation of kidney disease was initially reported in 1989 but has only recently gained broad acceptance among nephrologists and diabetologists (3). Familial Aggregation of DNThe notion that genetic factors contribute to any complex disease rests on the demonstration of familial aggregation. Familial clustering of nephropathy could result from shared genes, environmental exposures, or their combination.After repeated demonstra...