Today, because examining the whole genome has been so costly, most clinical and research labs look only at the exome, the roughly 1.5 percent of the genome associated with known functions.
You might say that we are only looking where we understand. The ability to sequence the whole genome affordably will now generate an abundance of data and an opportunity to understand the importance of many more genetic variants. Sequencing the entire genome typically finds hundreds of times as much variation between any two individuals as just sequencing their exomes, most of it in regions of the genome that are poorly understood.
Read the full, original story: The $1,000 Genome Is Here