First Study of NAT1 and NAT2 Polymorphisms in Bulgarian Patients with Balkan Endemic Nephropathy (Ben) and Healthy Controls

Etiology of Balkan endemic nephropathy and associated urothelial cancer

Balkan endemic nephropathy (BEN) is a familial chronic tubulointerstitial disease with insidious onset and slow progression to terminal renal failure. Evidence has accumulated that BEN is an environmentally induced disease. There are three actual theories attempting to explain the environmental cause of this disease: (1) the aristolochic acid hypothesis, which considers that the disease is produced by chronic intoxication with Aristolochia, (2) the mycotoxin hypothesis, which considers that BEN is produced by ochratoxin A, and (3) the Pliocene lignite hypothesis, which proposes that the disease is caused by long-term exposure to polycyclic aromatic hydrocarbons and other toxic organic compounds leaching into the well drinking water from low-rank coals in the vicinity to the endemic settlements. Moreover, it was suggested that BEN risk is influenced by inherited susceptibility. Therefore, it has been expected that molecular biological investigations will discover genetic markers of BEN and associated urothelial cancer, permitting early identification of susceptible individuals who may be at risk of exposure to the environmental agents. Since kidney pathophysiology is complex, gene expression analysis and highly throughput proteomic technology can identify candidate genes, proteins and molecule networks that eventually could play a role in BEN development. Investigation of gene-gene and gene-environment interactions could be the content of further studies determining the precise risk for BEN.

NAT2*5/*5 genotype (341T>C) is a potential risk factor for schistosomiasis-associated bladder cancer in Egyptians

Arylamine N-acetyl transferase (NAT2) displays extensive genetic polymorphisms that affect the rates of acetylation of drugs and genotoxic compounds such as amine carcinogens. To investigate whether the slow acetylator genotype is a risk factor for development of bladder cancer following schistosomal infection of the urinary tract, the authors determined the frequencies of 3 common polymorphisms in the NAT2 gene (341T>C, 590G>A, and 282C>T), which are associated with impaired acetylation activity, in control subjects (n=61; mean age 34.3+/-9.2 years) and in schistosomiasis-associated bladder cancer patients (n=55; 52+/-10.9 years) from the Egyptian population. Genotyping was carried out using rapid cycle PCR on the LightCycler, and subjects were assigned to a slow, intermediate, or rapid acetylator phenotype on the basis of the genotypes. The frequencies of the mutant alleles observed in the controls from the present study were similar to those reported previously for both the Egyptian population and other Arab populations. Patients showed a higher prevalence (78.2%) of slow acetylator phenotype than controls (67.2%), but this did not reach statistical significance (P=0.19). However, there were significantly more individuals who were carriers of 2 mutant 341T>C alleles (NAT2*5/*5 genotype) in the patient group compared with controls (odds ratio 2.6, CI 1.02-6.67, P=0.026). The alloenzyme encoded by this allele has been shown to display a large reduction in its catalytic activity. In conclusion, these data suggest that the NAT2*5/*5 genotype is a potential risk factor for development of urinary bladder cancer in patients with prior schistosomiasis infection.