Asp299Gly and the TLR4 Thr399Ile alleles was at least 6% in all populations tested. This frequency is sufficiently high to screen at-risk patients routinely for these mutations.In summary, we have developed a quick and reliable assay to determine the genotype of patients with respect to two common polymorphisms in the TLR4 receptor. The assay described in this paper allows the differentiation between patients who carry mutations at both loci and those who carry only one of the mutations. This discrimination may be important because there is an indication that the two mutations are of different severity and may confer a different amount of risk to the carrier. The simple PCR-based approach allows this genotyping assay to be performed in any laboratory with no need for expensive, specialized equipment. The assay uses standard molecular biology tools and common laboratory equipment and can therefore be performed in most clinical laboratories.