Human Genome Project
The human genome project is a effort to analyze the human DNA sequence. It started in the late 80's and continued through the 90's. Scientists say that a rough draft was basically completed in June 2000. The human genome has six billion base pairs. E-coli has 4,639,221. It was helped along with the increased use of the computer. You can find most of this information on pgs. 357-359 in your biology textbook.
To see a gene sequence click on this. HumanGenomeProject

Here is a picture of chromosome 1. Through the human genome project, they could found which base pairs were effected by the disease.
From U.S. Department of Energy Genome Programs and the website