It Takes a Genome: How a Clash Between Our Genes and Modern Life Is Making Us Sick

Three Reasons Why Genes Might Make Us Sick

The upshot of all this is that there are basically three ways that genetic variation can influence disease susceptibility. These are called the rare alleles, common variant, and small effect models. I will briefly describe each and then in the next section present a unified framework that iterates throughout the remaining chapters.

The simplest model is that a disease can be traced to one badly disrupted gene. This is pretty much the case for cystic fibrosis, and for thousands of other rare conditions. Around 1 in 100 of us carries a mutated version of the CFTR gene without any ill effects, but if two carriers marry, their children have a 1 in 4 chance of getting both bad copies and consequently having ...