Sequence variations in subjects with self-reported multiple chemical sensitivity (sMICS): A case-control study

Polymorphisms in several genes contribute to interindividual differences in the metabolism of xenobiotics, and may lead to toxicity and disease. The balance between activation and/or detoxification processes may influence an individual's susceptibility to disease. One postulated mechanism underlying multiple chemical sensitivity (MCS) is based on increased metabolism of xenobiotics. The aim of the present study was to determine such polymorphisms in cases with self-reported MCS (sMCS) and controls. sMCS cases (14 men, 45 women, mean age: 48 yr) and controls (14 men, 26 women, mean age: 44 yr) of the same anthroposphere were characterized using the MCS-questionnaire from Huppe and coworkers (2000) and a standardized questionnaire for living conditions and living factors. Allelic frequencies of genomic variations for 5HTT, NAT1, NAT2, PON1, PON2, and SOD2 were determined. The MCS questionnaire from Huppe et al. (2000) differentiated between cases and controls with 87.5% sensitivity and 90% specificity. Compared to controls the sMCS cases had lower exposures, especially to odorous factors, and worse social conditions. No significant differences of the allelic distribution of genetic polymorphisms in the genes for 5HTT, NAT1, NAT2, PON1, PON2, and SOD2 were found between cases and controls. The results are in contrast to the study of McKeown-Eyssen and coworkers (2004) but in accordance with the German MCS multi-center study. Although the MCS questionnaire from Huppe et al. (2000) allowed us to differentiate sMCS cases and controls, it was not strong enough for a discrimination based on sequence variations in genes for enzymes involved in xenobiotic metabolism.