This point is well illustrated in the case of coronary artery disease, in which cholesterol metabolism has long been thought to be a pathogenic pathway to disease.36 Although few pathogenic pathways are as well delineated as cholesterol metabolism, huge amounts of data pertaining to protein and pathway interactions have been obtained with the use of yeast, roundworms (Caenorhabditis elegans), and fruit flies (Drosophila melanogaster). Studies of these creatures have informed and continue to inform human genetic studies. For example, two of the genes that are involved in recessive parkinsonism, PARK2 and PINK1, have recently been shown to be involved in the same mitochondrial pathway through work in drosophila.37,38
