aBased on a simple linear dose–response model adjusted for sex, age at examination by sex, oblast of residency, urban or rural residency, current smoking, ATPO and ATG levels, examination year, urinary iodine excretion levels, presence of goiter. bp-Value of maximum likelihood ratio test comparing the fit of models with and without interaction terms. cSubjects with unknown smoking status excluded from the analysis. dSubjects with unknown goiter status excluded from the analysis. The gene discussed is ATP5PO; the disease is goiter.