The present study included both of SNP loci in MTHFR gene, and the result showed that BD-exposed workers carrying MTHFR C677T C allele had significantly lower NBUD frequencies than those carrying TT genotype, which validated that MTHFR C677T T allele may play a pronounced role in human genetic susceptibility towards BD-induced mutagenicity. Here, MTHFR is linked to Behcet disease.