What are your thoughts about this new blood test to diagnose depression?

“Researchers at the Medical University of Vienna have demonstrated the possibility of using a blood test to detect depression. While blood tests for mental illnesses have until recently been regarded as impossible, a recent study clearly indicates that, in principle, depression can in fact be diagnosed in this way and this could become reality in the not too distant future. ...Researchers… used functional magnetic resonance imaging of the brain and pharmacological investigations to demonstrate that there is a close relationship between the speed of the serotonin uptake in blood platelets and the function of a depression network in the brain.”
Depression is Detectible in the Blood

The good news is this experimental blood test can help diagnose and treat depression.
The bad news is that it can potentially be misused in many ways.
Will employers ask prospective candidates for a blood sample as well as a urine sample?
What other possibilities, good and bad, do you see?