Over the last two decades, scientists have primarily used two strategies to study the genetics of common diseases like diabetes and schizophrenia. One involves looking for links between disease and common genetic variants such as single nucleotide polymorphisms (SNPs) that are scattered throughout the genome. The other, more recent approach focuses on the protein-coding portion of the genome (the exome) to find ultra-rare mutations (ones that might appear in tenths or thousandths of a percent of the population) that are difficult to find in genetic studies, but which can dramatically increase disease risk.
