As part of the multicentric MCS study carried out by the Robert Koch Institute in collaboration with the University of Goettingen (Department of Clinical Pharmacology) with the participation of the German MCS research network, blood samples from 205 outpatients attending environmental medicine clinics (136 women (66.3 %), 69 men (33.7 %), mean age 49 years) were investigated for 26 variants in 17 genes. Literature research had suggested the hypothesis that these gene variants could be associated with increased sensitivity to chemicals in the environment. Some of the selected gene variants are considered by individual environmental clinicians and laboratories offering such tests to be markers for increased sensitivity to chemicals (markers of the so called MCS). The object, therefore, was to establish whether the selected allele variants were more frequent in outpatients of environmental medicine clinics than in various control groups and whether any differences in frequencies were sufficiently marked to provide the basis for a diagnostic strategy. For the molecular genetic analyses, 205 consecutive blood samples from 5 outpatient clinics for environmental medicine were available. The allele frequencies in the group of environmental medicine outpatients were, after appropriate adjustment for alpha errors, not significantly different from the frequencies for the Caucasian/European population known from other studies. Nor were there any statistically significant differences in the genotypes of the environmental medicine outpatients with selfreported MCS (sMCS) and those of the non-sMCS patients. The study yielded no evidence of a diagnostically useable excess of certain gene variants in outpatients attending environmental medicine clinics or in persons who consider themselves to have MCS. Such molecular genetic test results are therefore not considered to be of diagnostic relevance at the present time for outpatients attending environmental medicine clinics and exposed to low doses of chemicals.
