…through metabolites:

Douglas Kell, a researcher at the University of Manchester in Britain, has already created a computer model based on metabolite profiles in blood plasma that can single out pregnant women who are developing pre-eclampsia, or dangerously high blood pressure. Research published last year by Rima Kaddurah-Daouk, a psychiatrist at the Duke University Medical Centre in America, may not only provide a test for schizophrenia, but also help with its treatment. She found a pattern of metabolites present only in the blood of people who had been diagnosed with schizophrenia. The patterns change according to the antipsychotic drugs patients take and this may throw light on why some respond well to certain drugs, but others suffer severe side-effects.

This seems very promising, and near term. This part is a little misleading, though:

Studying genes alone does not provide such detail. Genes are similar to the plans for a house; they show what it looks like, but not what people are getting up to inside.

This implies that the genome is a blueprint–that the body is built by following a plan. But that’s a bad analogy. A much better one is a recipe. First do this, then do that. If it were a blueprint, identical twins would be truly identical, and indistinguishable. But because it’s a recipe, there are subtle differences (e.g., fingerprints) because the genome doesn’t specify the body design to that high a level of detail, and much can depend on womb environment (one reason to think that this could be a strong factor in the creation of homosexuals, in addition to genetic predisposition).