What an open question !

I think we may be able to achieve such a goal with our current tools from molecular biology including genomic analyses and others. At least for some diseases.

The main issue is the health system. Molecular analyses are still very expensive, and even if they become more affordable, it will never be possible to predict diseases in the whole population.

For instance, how can you justify the predictive analysis of colon cancer in a random population. Of course, some individuals in this population will develop colon cancer, but how much will it cost to perform a molecular analysis for all of them ?

I think the question is rather : how can we screen each individual for a wide range of diseases, in a cost-effective manner ?

Really an open question as David said. You did not specify the type of disease. Several factors needs to be considered including the aetiology of a diseases. For example there are inherited disease such as sickle cell anemia which is as result of a single nucleotide mutation adenine to thymine (glutamic acid to valine) at position 6 of Beta globin gene. Molecular tools could be used to detect this disease at early stage and it is hope that gene therapy might be used to treat it. Another disease is the female breast cancer in which BRCA1 and BRCA 2 gene mutation have been known to be associated with increased risk of female breast cancer. Although several other factors are associated with increased risk. The completion of the Human Genome Project (HGP) has enabled us to be step ahead in detecting many disease before they could manifest or strike. Some countries have made it mandatory to detect some prevalent disease at the antenatal /prenatal stage.

@David_Muller, @Nasiru_Abdullahi, the above question is more general. Specifically I should have asked, in an individual, can we identify genetic risks of various diseases such as cardiac, diabetic,metabolic disorders, cancer.

Mubasher: You will also need to consider epigenetics, gene expression, gradual decay (due to the accumulation of damage), FUTURE environmental (and behavioral) effects on the genome and its expression, and RANDOM mutations. The complexity is just enormous. And imagine you test me today and you find out I look 10 years younger and all that and so on, and tomorrow I will decide to start eating 1 pound of sucrose per day . . .

But you can create population-wide models and test them in Monte Carlo simulations to see the range of outcomes and probabilities of various scenarios. But you will have to get the consent from many people to voluntarily subject themselves to the genetic examination. Some might not be willing to participate. What will you do? Lobby the government to create and pass the law for mandatory genetic examination? What will you do with people (like myself) not willing to obey such law?

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Interventions in complex systems usually make things worse.

Dear Martin, neither I am talking about the law and order problem, nor I am talking about Lobbying or things like that. Can you please have a second look on my question. It is so interesting... You have rushed to the conclusions and consequences.

Mubasher: Assuming that one knows all major contributing factors to a particular disease, and their relative weights, and one takes into account the interaction of the individual with his/her environment, and assuming a regular follow-up in all the monitored parameters, then one can, in principle, assess the risk of a particular disease, ideally in regular intervals, and alert the individual about any change in the risk and the cause of the change, and suggest interventions or lifestyle changes to mitigate the risk. I think this is possible. But, personally, I do not want to know my individual risk of diseases. It just does not interest me at all.

You mentioned "diabetes", "metabolic disorders" and "cancer" among the examples, but if there is any disease that I can see right now spreading across the world like a wildfire, it is the crazy obsession of people with "health" and "security". (It will backfire. The individual freedom will be lost.) For me, life is fun, if I am free to do, what I want to do, and if there is some element of danger in it. I'd rather take my chances than be constantly monitored by 360-camera systems and the "health care" provider (with a backdoor wide open to the government), chastising me about the second lemon drop.

But death comes with 100% risk. There is both danger and certainty. A perfect combination?

Martin: You said life is a fun...Now assume that you have a risk of a particular disorder(may it never happen) in some stage of your life. Now how would you feel if that disorder is detected and cured with time ?? You will simply feel like a champion, isn't it ?? What I actually feel is that you are just looking into one side of the story.

Mubasher: You are right. Absolutely. When the crunch-time comes, I will wonder why don't I have a copy of my own heart ready for replacement. Plug and play.

In fact, there are already some publicly-traded companies that offer genetic tests to identify hereditary risks, e.g., for breast and prostate cancer (Myriad Genetics, Roche, etc.). It would be awesome if they could identify the Gloomy gene. I must have some extra copies on every chromosome.

Joking aside, the problem is that there rarely is a direct link between genome and disease; and the genome undergoes genetic and epigenetic changes throughout the life but not uniformly within the body, and not very predictably anyway. The body gradually becomes a bizarre genetic mosaic.

One wrongly weighted factor can render the analysis meaningless. False positives could also ruin some people's lives, psychologically and physically.

On the other hand, there are often early warning signs that "something is wrong". And most such signs can be detected by the individuals themselves if they "listen to their bodies and minds".

As for some quantitative biomarkers, "liquid biopsy" is an emerging field in disease diagnostics and monitoring; seems a better idea to me than genetic tests alone. But will it ever be as cost-effective as "listen to yourself"?