Methodologic quality and genotyping reproducibility in studies of tumor necrosis factor -308 G→A single nucleotide polymorphism and bacterial sepsis: Implications for studies of complex traits

Dixie L. Peters, Robert C. Barber, Elizabeth M. Flood, Harold R. Garner, Grant E. O'Keefe

Research output: Contribution to journalArticle

35 Scopus citations


Objective: Studies of genetic associations with common diseases, such as between cytokine gene polymorphisms and severe bacterial sepsis, have reached conflicting conclusions. Failure to follow methodologic standards may have contributed to discordant findings. The -308 G→A transition in the tumor necrosis factor-α promoter has been genotyped by a variety of methods. Based on our observation of genotyping inaccuracies, we sought to determine whether published studies followed a series of acceptable methodologic standards and whether failure to follow the standard of genotyping reproducibility could lead to erroneous conclusions about gene-disease associations. Design: Systematic review and reanalysis of banked genetic material. We applied a published series of seven methodologic standards to five reports of the association between this variant and bacterial sepsis. We then studied the accuracy of restriction fragment length polymorphism for the -308 site using DNA from a cohort of injury victims. Setting: Surgery research laboratory. Measurements and Main Results: We observed that methodologic quality was not uniform and that reproducibility of genotyping was infrequently met. In our subjects, we found that 4 of 46 heterozygotes analyzed by restriction fragment length polymorphism were actually GG-homozygotes (9% misclassified) according to alternative genotyping methods. Conclusions: Failure to confirm genotype may have led to conclusions that this polymorphism is not associated with sepsis or outcome. Our observations have implications for the conduct and evaluation of studies of complex genetic disease.

Original languageEnglish
Pages (from-to)1691-1696
Number of pages6
JournalCritical Care Medicine
Issue number6
StatePublished - 1 Jun 2003



  • Bacterial sepsis
  • Genotyping
  • Tumor necrosis factor-α

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