Primary hyperoxaluria (PH) is an autosomal-recessive disorder of endogenous oxalate synthesis characterized by accumulation of calcium oxalate primarily in the kidney. Deficiencies of alanine-glyoxylate aminotransferase (AGT) or glyoxylate reductase (GRHPR) are the two known causes of the disease (PH I and II, respectively). To determine the etiology of an as yet uncharacterized type of PH, we selected a cohort of 15 non-PH I/PH II patients from eight unrelated families with calcium oxalate nephrolithiasis for high-density SNP microarray analysis. We determined that mutations in an uncharacterized gene, DHDPSL, on chromosome 10 cause a third type of PH (PH III). To overcome the difficulties in data analysis attributed to a state of compound heterozygosity, we developed a strategy of "heterozygosity mapping"-a search for long heterozygous patterns unique to all patients in a given family and overlapping between families, followed by reconstruction of haplotypes. This approach enabled us to determine an allelic fragment shared by all patients of Ashkenazi Jewish descent and bearing a 3 bp deletion in DHDPSL. Overall, six mutations were detected: four missense mutations, one in-frame deletion, and one splice-site mutation. Our assumption is that DHDPSL is the gene encoding 4-hydroxy-2-oxoglutarate aldolase, catalyzing the final step in the metabolic pathway of hydroxyproline.

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Oxidative stress and inflammation have recently been linked to endothelial damage in essential hypertension (EH). Activated peripheral polymorphonuclear leukocytes (PMN) damage surrounding tissue by releasing reactive oxygen species (ROS) and proteolytic enzymes before self-necrosis. PMN necrosis further exacerbates inflammation and promotes chemotaxis and PMN recruitment. The number and properties of PMN from untreated EH patients is the focus of the present study. Oxidative stress was assessed by measuring the rate of superoxide anion release from separated, phorbol ester-stimulated PMN and the redox state of plasma glutathione. Inflammation was estimated indirectly by determining PMN number and their in vitro survival. PMN from EH patients (n = 37) released superoxide anion faster (P < .0001) than those of normotensives (NC, n = 37), 17.7 +/- 1.14 v 9.54 +/- 0.51 nmol/10 min/10(6) cells. The redox state of glutathione was twofold higher in EH plasma (P < .02) indicating systemic oxidative stress. PMN survival in vitro correlates linearly with the rate of superoxide release (r2 = 0.60, P < .02) and PMN count of EH patients, although in the normal range, were significantly higher (P < .0001), indicating necrosis and recruitment. Hypertensive plasma significantly reduced NC PMN viability, whereas normal plasma significantly increased EH PMN viability. What our studies show is that EH is accompanied by a primed state PMN that does not correlate with the levels of blood pressure. PMN priming in EH patients reflects an in vivo exposure to a constant stimulus ending in oxidative stress, increased self-necrosis, and cell recruitment. Oxidative stress and inflammation will result in endothelial damage and atherosclerosis in the long run.

Primary hyperoxaluria type 1 (PH1) is a rare, progressive, genetic disease with limited treatment options. We report the efficacy and safety of lumasiran, an RNA interference therapeutic, in infants and young children with PH1. Methods: This single-arm, open-label, phase 3 study evaluated lumasiran in patients aged <6 years with PH1 and an estimated glomerular filtration rate >45 mL/min/1.73 m 2 , if aged ≥12 months, or normal serum creatinine, if aged <12 months. The primary end point was percent change in spot urinary oxalate to creatinine ratio (UOx:Cr) from baseline to month 6. Secondary end points included proportion of patients with urinary oxalate ≤1.5× upper limit of normal and change in plasma oxalate. Results: All patients (N = 18) completed the 6-month primary analysis period. Median age at consent was 50.1 months. Least-squares mean percent reduction in spot UOx:Cr was 72.0%. At month 6, 50% of patients (9/18) achieved spot UOx:Cr ≤1.5× upper limit of normal. Least-squares mean percent reduction in plasma oxalate was 31.7%. The most common treatment-related adverse events were transient, mild, injection-site reactions. Conclusion: Lumasiran showed rapid, sustained reduction in spot UOx:Cr and plasma oxalate and acceptable safety in patients aged <6 years with PH1, establishing RNA interference therapies as safe, effective treatment options for infants and young children.