HapMap - Finding the top 300,000 human genetic differences

In a recent article, Francis Collins, one of the leaders of the Human Genome Project, proclaimed that "the HapMap is generating a gold-standard set of [gene] variants".

So, what is this new HapMap project?  It's an international $100 million project slated for completion in 2005, and funded in the U.S. by the National Institutes of Health.  The goal of HapMap is to find many of the gene variations among humans that make us different from each other.

The HapMap project is a follow-on to the Human Genome Project.  That project, which completed a few years ago, identified the 20,000 gene locations we all share, but not the gene variants at each location.  Essentially, the Human Genome Project identified the genes of only one person (Craig Venter), a healthy, white, male, high-IQ, extroverted caucasian.

The HapMap project acknowledges that we all share over 99% of the same genetic material, but since we all have 20,000 genes comprising 3 billion "DNA letters", having a 1% genetic difference translates to millions of variations between people.  (Remember that two keys need have only 1 difference in order to open two different locks!)

The HapMap project found that "only" 300,000 or so of these differences comprise the most important set, responsible for differences in disease susceptibility, personality differences, etc.  When those differences are measured, and correlated with the results of questionnaires, we can find out which genetic difference leads to which effect.

Hot Button Issue: For example, if a significant number people who are found to have gene variant XYZ answer "yes" when asked if they have ever committed a crime, that gene variant may be responsible for a lower threshold to anger and aggressive behavior.