Genetic Studies Claiming Gender Differences Often Flawed
Many insufficiently documented or spurious
TUESDAY, Aug. 21 (HealthDay News) -- Studies that claim that the genetic effects for common diseases or traits vary depending on gender are often insufficiently documented or spurious, researchers report in the Aug. 22/29 issue of the Journal of the American Medical Association.
John P.A. Ioannidis, M.D., from the University of Ioannina in Greece, and colleagues reviewed 77 published genetic-association studies containing 432 claims of sex differences for genetic effects.
The researchers found that 66.2 percent of studies claimed that sex comparisons were decided a priori. Only 12.7 percent of claims had appropriate documentation of gene-sex interaction, while the remainder of claims were insufficient or spurious. Of 188 claims with data for reanalysis, 44.1 percent were nominally statistically significant (p=0.05 threshold), and 53 percent of these had modest p values of 0.01 to 0.05. Only one of 60 claims that appeared to have good internal validity was consistently replicated in at least two other studies.
"In this sample of highly prominent claims of sex-related differences in genetic associations, most claims were insufficiently documented or spurious, and claims with documented good internal and external validity were uncommon," the authors conclude.