The effect of noise in studies of the association of bone mineral density and vitamin D receptor gene

To find defects in genes that cause diseases, geneticists test whether a change or variation in a gene is associated with a disease or an increased susceptibility. M.A. Morrison et al. (1994) reported that a slight variation in the vitamin D receptor gene (VDRGP) is associated with a significant change in our bone mineral density (BMD). By January 1997, 75 independent investigations had been published, and no consensus had been reached as to whether BMD is really associated with VDRGP. Every paper has a level of noise which leads to possibly inaccurate conclusions. Some examples of noise are small sample size, large age range, heterogeneity of the populations studied, and so on. We analyzed all the 75 publications using a fuzzy mathematics approach to determine the noise level of each paper and how it affected the papers' findings. We showed, except for one exception, that there is a strong association between the noise level and the papers' findings.