Verified predominance of slow acetylator phenotype N-acetyltransferase 2 (NAT2) in a Hmong population residing in Minnesota

Southeast Asians known as the Hmong have a high prevalence of tuberculosis and select cancers. The slow acetylation (SA) phenotype for N-acetytransferase 2 (NAT2) has been associated with toxicity from the anti-tuberculosis drug, isoniazid and in increased risk of select cancers. Previous research indicates a 74.5% prevalence of SA in Hmong which differs from other Asian populations including the Japanese and Thai (range: 7%-45%). Given this contrast, the purpose of this study was to confirm or refute this unexpected predominance of the SA phenotype in Hmong. Unrelated, Minnesota Hmong between 18 and 65 years of age consented and participated by ingesting caffeine as the probe for NAT2. A urinary caffeine metabolic ratio AFMU/1X (<0.6) was used to classify subjects as slow acetylators. Among 51 analysable samples provided by 61 enrollees (27 male, 33 female, 1 sex unknown, age 30 ± 11 years [mean ± SD]) there were 47 (92.2%) slow and 4 (7.8%) rapid acetylators. The prevalence of the SA phenotype (92.2%) from this study exceeds the 74.5% (p < 0.02 by chi-square test) previously noted in Minnesota Hmong (n = 98). The predominance of the SA phenotype within Minnesota Hmong is confirmed. Further studies evaluating this unexpected prevalence, its genetic basis and potential clinical relevance to drug toxicity and disease are warranted.