Paraoxonase activities in Minnan and Hakka

Three phenotypes of paraoxonase (PON) have been found in population studies. The B type gene frequency varies among different populations. The Singaporean Chinese gene frequency is trimodal. The gene frequency of British Chinese populations was neither bimodal nor trimodal. We conducted a study to determine the frequency distribution of PON in the Minnan and Hakka populations. We collected blood samples and questionnaires from Minnan and Hakka subjects from Nantou County, Taiwan, excluding those with PON confounding factors. The blood samples were then examined for PON-non-NaCl (PON without salt stimulation), PON-NaCl (PON with salt stimulation) and arylesterase activities. We compared median differences in age, sex, PON-non-NaCl, PON-NaCl, arylesterase, and PON-NaCl/arylesterase between Minnan and Hakka populations using chi-square and rank analysis of variance (ANOVA), adjusted for age. There were 258 Minnan and 67 Hakka subjects without confounding factors. None of the frequency distributions for PON-non-NaCl, PON-NaCl, or PON-NaCl/arylesterase was clearly bimodal or trimodal. Hakka were older and had increased PON-non-NaCl, PON-NaCl, and PON-NaCl/arylesterase when compared with Minnan, but only age and PON-non-NaCl were significantly different. Hakka and Minnan may have more heterozygous AB phenotype for PON, which might explain why the frequency distribution is not trimodal or bimodal. Marriage among Minnan, Hakka, Aborigines, and other Mainland Chinese in Taiwan may be responsible for difficulty in differentiating gene frequencies among subpopulations by PON phenotype. Nonetheless, the Hakka appeared to have greater PON activity than the Minnan. Subpopulation in itself may be a factor for higher PON activity among the Hakka after controlling for confounding factors.