Table 2.

Research Targets in Genetic Variation and Disease Association Studies Before and After the Human Genome Project

Before the Human Genome Project	After the Human Genome Project
Mutations in one or a few genes	Genetic variations in many genes
Protein-coding genes	Protein-coding genes and RNA
Protein-coding regions in a gene	Intragenic regions (introns); regulatory elements; intergenic regions
Mainly point mutations	SNPs; short insertions and deletions; copy number variations; other structural variations
Individual genes	Gene-gene interactions; gene-environment interactions
One single gene or a few genes per study	Tens of thousands of genes or the whole genome in one study