Genetic tests are currently available for specific genetic disorders, but the Wellcome Trust Case Control Consortium is looking at the more mild and multiple genetic variations which combine with environmental factors to give a person an increased risk of developing a disease.
Integrating multiple genetic variations with respective weight, which results in polygenic scores as used in many diseases (Dudbridge, 2013), could be applied in microbiome research to explain the underlying genetic architecture for a single taxon or the overall diversity and would yield a more complete overview of host-microbe cross-talk.
Thus, the exploration of multiple genetic variations interacting with multiple environmental factors may be needed.
Multiple genetic variations are associated with type 2 diabetes, but family history remains the only feasible measure of "genetic load" that can be used on a population level.
Actually, evidence has showed that some loci confer risk for more than one of the studied diseases, and most common diseases arise from interaction between multiple genetic variations.
Analogous to these findings, we hypothesized that carrying multiple genetic variations in multiple PRRs (in a so-called carrier trait) may increase the risk of C. trachomatis-associated tubal pathology in subfertile women.
In this aspect, it is important to mention that in most cases multiple genetic variations result in a disposition to a particular disease and each variant makes a small contribution to the overall susceptibility to pain.
This suggests that if positive directional selection for slow-causing NAT2 haplotypes in specific dietary and environmental conditions has been acting on the genetic evolution of populations, such selective pressures might have acted on multiple standing genetic variation rather than on specific new NAT2 mutations [ 25, 26, 38, 43, 77].
Consistent with the evidence observed for KCNQ1, our finding highlighted that multiple common genetic variations within the same gene region may independently contribute to disease risk [ 6, 12].
In contrast, full re-sequencing surveys, in which the sequence of a genomic segment is determined in each individual in the sample, allow an unbiased characterization of multiple aspects of genetic variation and are suitable for standard methods of population genetics analyses.
