SHORT COMMUNICATION: Genotype/phenotype discordance for human arylamine N-acetyltransferase (NAT2) reveals a new slow-acetylator allele common in African-Americans

Abstract

Carcinogenic arylamines are acetylated by the hepatic N-acetyltransferase. This enzyme is polymorphic in humans and in some epidemiological studies, the slow-acetylator phenotype has been associated with higher risk of bladder cancer and lower risk of colorectal cancer. The presence of two germline copies of any of several mutant alleles of the NAT2 gene produces a slow-acetylation phenotype. We used a PCR-RFLP technique to identify three known slow-acetylator alleles (M1, M2 and M3). Comparison of results from PCR-RFLP genotyping with caffeine metabolism phenotyping in 42 individuals suggested that an additional slow-acetylator allele was present in our sampled population. We sequenced the NAT2 gene for several discordant slow-acetylator individuals and found a G > A base-change in codon 64 that caused a Arg > Glu amino acid substitution. This sequence change, termed the 'M4' allele, was found in all of the discordant individuals in our population and apparently causes a slow-acetylation phenotype. In addition, we have determined that NAT2 allele frequencies in 372 Caucasian-Americans (WT = 0.25, M1 = 0.45, M2 = 0.28, M3 = 0.02, and M4 = 0.00) and in 128 African-Americans (WT = 0.36, M1 = 0.30, M2 = 0.22, M3 = 0.02 and M4 = 0.09) are significantly different (P < 0.0001). The M4 allele was not found in 372 unrelated Caucasians and appears to be of African origin.

Pharmacogenetics of the arylamine N-acetyltransferases

“…Nine of these lead to a change in the encoded amino acid (C 190 Several studies have been performed that show clear correlations between NAT2 genotype and phenotype. [53][54][55] Early genotyping studies screened for the presence of the C 481 T (M1), the G 590 A (M2), the G 857 A (M3) and sometimes the G 191 A (M4) nucleotide changes, all of which were shown to cause a slow acetylation phenotype. Moreover, there was a gene-dosage effect.…”

DNA repair gene polymorphisms, bulky DNA adducts in white blood cells and bladder cancer in a case-control study

“…Rapid-acetylator genotypes are wild-type allele homo-/ heterozygotes; slow-acetylator genotypes are those with 2 slowacetylator alleles. 28 PCR followed by enzymatic digestion was also used for genotyping of XRCC1-Arg399Gln, XPD-Lys751Gln and XRCC3-Thr241Met polymorphisms. All PCRs were performed in a total reaction volume of 20 l containing 10 ng genomic DNA, 0.4 units of Taq polymerase (Perkin-Elmer Applied Biosystems, Foster City, CA) in PCR buffer 1ϫ, 1.5 mM MgCl 2 , 50 mM dNTPs and 250 nM of each primer.…”

Association of genotypes of carcinogen‐activating enzymes, phenol sulfotransferase SULT1A1 (ST1A3) and arylamine N‐acetyltransferase NAT2, with urothelial cancer in a Japanese population

“…A NAT2 high-activity allele, NAT2*4, and NAT2 low-activity alleles, NAT2*5, NAT2*6 and NAT2*7, were determined according to a previously published PCR-RFLP method. 19 A NAT2 variant allele (NAT2*14), which is very rare (less than 1% frequency) in the Japanese population, was not considered. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by multiple logistic regression analysis using the JMP program package (Version 3, SAS Institute, Cary, NC).…”