ThinkGene has a nice critical post reviewing some of deCODE Genetics’ advertising. The main idea is that genetic tests as yet provide almost no information worth acting upon in a course of treatment.
So, since there is no evidence, only decision to take action, you could replace the deCODEme test with a homeopathic test that produces the same ratio of positive results for the same clinical effect. I understand that people sometimes feel they need a special reason to pursue healthcare from which they could always hypothetically benefit, but there is no rational necessity to produce this impetuous prior to treatment other than the psychological comfort of rationalization.
He concludes that some of the claims are essentially the same as magic, since they have no evidence-based support.