How will personal sequencing impact medicine?

Currently, having your genome sequenced would be similar to having thousands of genetic tests done at the same time – you would learn quite a bit about your genetic make-up, but the information that would be gleaned from your sequence would be limited to the parts of the genome that are already well understood. However, if many people have their DNA sequenced and provide their medical history as well as a detailed physical description of themselves, personal genome sequencing could be a powerful tool for learning more about the parts of the genome that are poorly understood. 

Essentially, the power of sequencing comes from the exercise of comparing genotype and phenotype; by analyzing the genomic sequences (genotypes) and physical characteristics (phenotypes) of millions of people, personal genome sequencing has the potential to link specific traits to specific genes. The most obvious benefit of these analyses will be to better understand the interplay of nature and nurture in known diseases, with the hope that they would lead to better treatments, cures, preventative measures, and healthier generations of children.