Technology today doesn't only make our lives easier, it may as well save us. Getting full information on a patient's health is of crucial importance to doctors, they need to make the right call, correctly diagnose and put the patient on the right medication.
In most cases doctors would only need information about your recent diseases, but sometimes it is insufficient, and then the whole process becomes hell of a paperwork. This is the case with genomic sequencing. Genomic sequencing (or DNA sequencing) is a very complex process that allows to reconstruct the patient's DNA and, consequently, determine the treatment that would be the most (and sometimes even the only) effective one for this or that patient.
But how does Google fit in? Well, the guys would like to make «a small contribution toward helping the medical profession find new, proactive ways to keep us healthy». The tech giant is going to conduct a «Baseline Study» and use its powerful tools for analyzing the patient's data. The company plans to start off with 175 people and collect their blood, saliva and other samples for analysis. No, you won't have to spit on your monitor or put your hair into the CD-ROM, the samples will be gathered by healthcare institutions and will be delivered to Mountain View with all the personal data deleted.
But the point is that Google will get your full genome sequence — the thing that may tell even more about you than your fingerprints or even Google's search engine — so it is rather difficult to speak about anonymity here. Nevertheless, all the data will remain within Google and won't be shared publicly, so there is no reason to become paranoid. Well, only in case you think that Google can use it one day to take over the world or create an army of clones.