Brunner and his colleagues used a technique called exomesequencing, which extracts only known genes from the vast expanse of DNA in the human genome as a way to reduce sequencing cost.
Further more exomesequencing is a questionable working model as companies will now be able to sequence a complete genome at a lower cost than one utilizing array exome capture and potential bias, why a company would offer that as the preferred service is odd.
See, for instance, this case I wrote about a year ago, or this one, in which sequencing the part of the exome that was on the X chromosome allowed scientists to figure out the cause of a genetic disease that was killing young boys in a Utah family.