[9][6][10] Suitable candidate genes are generally selected based on known biological, physiological, or functional relevance to the disease in question.
Genome-wide association studies (GWAS) and quantitative trait locus (QTL) mapping examine common variation across the entire genome, and as such can detect a new region of interest that is in or near a potential candidate gene.
[13] In addition, the availability of genetic information through online databases enables researchers to mine existing data and web-based resources for new candidate gene targets.
For instance, the candidate-gene approach has been shown to produce a high rate of false positives,[22] which requires that the findings of single genetic associations be treated with great caution.
[26] In a study by Kim et al., genes linked to the obesity trait in both pigs and humans were discovered using comparative genomics and chromosomal heritability.
One example of manipulating candidate genes can be seen in a study completed by Martin E. Feder on heat-shock proteins and their function in Drosophila melanogaster.
[28] Feder designed a holistic approach to study Hsp70, a candidate gene that was hypothesized to play a role in how an organism adapted to stress.
The different approaches this study took included both genetically modifying the candidate gene (using site-specific homologous recombination and the expression of various proteins), as well as examining the natural variation of Hsp70.
The manipulation of candidate genes is also seen in Caspar C. Chater's study of the origin and function of stomata in Physcomitrella patens, a moss.