Butyrylcholinesterase variants (BCHE and CHE2 Loci) associated with erythrocyte acetylcholinesterase inhibition in farmers exposed to pesticides.

Farmers exposed to pesticides and classified as mildly poisoned and controls on the basis of erythrocyte acetylcholinesterase (AChE) activity were examined for butyrylcholinesterase (BChE) genetic variability. The mildly poisoned group showed a significantly higher frequency of non-usual phenotypes (13.1%) than the control group (1.7%). These phenotypes showed a relative risk (RR) of 8.8 of erythrocyte AChE inhibition when compared to the usual phenotype. Among the subjects with the usual phenotype, the CHF2 C5- phenotype was more frequent in the mildly poisoned group (94.3%) than in the control group (81.0%), leading to an RR of 3.9 when compared to the CHE2 C5+ phenotype. When the total sample was classified into two groups (usual CHE2 C5+ and other phenotypes), the usual CHE2 C5+ phenotype was found to be responsible for a preventive fraction of about 14% of the cases of mild poisoning. The present data suggest that BChE genetic variability offers differential protection against erythrocyte AChE inhibition.