“If you can look into the seeds of time
And see which grain will grow and which will not”.
Shakespeare in Macbeth.
Sometime in the not too distant future, scientists hope to be able to routinely predict specific diseases, an infant will be susceptible to over the entire course of his or her life. Such a development, if and when it takes place, would not only revolutionise medical therapy but also radically alter our entire approach to the war against diseases.
It has been predicted by few scientists not without some justification that as our concept of what constitutes a hereditary disorder broadens,‘genetic counselling’ will no longer be limited to those who are concerned about their offspring having a birth defect (haemophilia and sickle-cell anaemia which are clear cut examples of genetic disorders) but how they view diseases like duodenal ulcers, fibrositis and skin cancers.
Such information would enable doctors as well as lay person to take practical steps well in advance. For example, the parents of a child who is thought to be vulnerable to skin cancer may take decision to leave their home, situated in a sunny region, say Delhi, and migrate to a place exposed to a less sunny climate in some other part of the country, say Darjeeling. A teenage boy who is likely to fall victim to painful fibrositis in middle age may take a decision not to pursue a strenuous athletic career that would only aggravate his condition. If a person knows that he has a predisposition to ulcer, the awareness may influence the individual’s choice of diet or even his or her lifestyle.
No standardised method of plotting a personal indexing of probabilities has yet been worked out, but one approach hinges on the discovery of what are called ‘HLA antigens’. These first came to light because they affect the acceptance or rejection of tissue grafts. Just as blood groups determine the types of blood that can be transfused from one person to other, so HLA antigens must be matched if a kidney or other organ is to be successfully transplanted. These antigens occur in white blood cells and tissues and their myriad subdivisions constitute a‘chemical fingerprint’.
As immunologists began analysing HLA antigens, it became apparent soon that antigen patterns provided tell-tale signs of our predisposition to different diseases, such as rheumatoid arthritis (a chronic inflammatory disease which affects the joints), multiple sclerosis (a degenerative disease of the central nervous system that causes among other things neurological disturbances, psoriasis (a skin disease that causes enormous discomfort and suffering) which are among the conditions known to be influenced by them; and the list is growing steadily. HLA antigens might radically transform genetic counselling as we now know it.
The profession’s rapid advancement is also due to parallel findings that have emerged from a closely related field. While one group of researchers have focussed on HLA antigens or cell-surface markers, others have probed inside the cell to study chromosome abnormalities. Such a technique is used by cytologists who disqualify female Olympic athlete whose cells show signs of illicit intersexing, but its greatest potential may be to highlight disease proneness. A few years ago some serious research was carried out in the UK to study the prospect of distinguishing between tobacco smokers who are vulnerable to lung cancer and those who are comparatively resistant. In particular the work done by one researcher revealed that some cigarette smokers had significantly more chromosome defects in one type of white cells compared with non-smokers. Moreover, a particular chemical even in vanishingly tiny amounts causes these cells to mutate. Studies are now under way to compare the response of cells from lung tumour patients and those from healthy ‘controls’. The next step is to learn whether this approach can be extended routinely to identify sensitive individuals.
There are further indications that such an exercise may be rewarding. Already one cell defect, the so-called Philadelphia chromosome, in some types of leukaemia has been linked unambiguously with cancer. More recent reports suggest that subtle chromosome abnormalities are also associated with cancer of the kidney and with several other forms of leukaemia i.e. blood cancer.
The concept of being able to guess disease susceptibility at a later stage in life is a revolutionary one. Knowing what may be in store could lead to radical changes in people’s careers, lifetimes and expectations. Some people may, however, erroneously argue that the ability to predict disease in this fashion at an early stage of one’s life is not only not necessary but may also lead to social complications. For example, one misleading argument could be that an individual who knows that the person he or she is in love with may develop cancer at a later date, can make other plans by dropping the idea of getting married to that person. This would be actually a right approach though it may cause mental agony to both the parties involved at that point of time. It should in fact be viewed perhaps as a blessing in disguise. Blissful ignorance of a possible future adverse development, especially when one can predict it with a degree of certainty in the case of one’s a health, can never be justified under any circumstance! The impact of these fields of research on future social patterns would be immense. Tomorrow’s doctors would be able to give us uncanny precise information about our future medical profile. Whether we will take heed of that advice would be, of course, entirely a different question. But nobody can belittle the value of useful medical information, if made available to a person at a sufficiently early state in his or her life. Over the ages, man has seen many developments and witnessed many successes in the field of medicine and medical technology. Major illnesses have been tackled with the help of vaccines which prevent many diseases and antibiotics which cure a large number of ailments.
For the first time Scientists are beginning to entertain the view that the task of predicting the risk of disease involves screening currently-healthy individuals by genome analysis at the individual level. They believe that intervention with lifestyle changes and drugs can be recommended well before the onset of disease. However, they concede that this approach is most applicable when the problem resides within a single gene defect. Such defects only account for approximately five percent of diseases in developed countries. Most of the common diseases, such as heart disease, are multi-factored or polygenic, which is a phenotypic characteristic that involves two or more genes interacting with environmental factors such as diet. In April 2010, scientists at Stanford University published the genome analysis of a healthy individual scientist at Stanford University, who had his genome sequenced; the analysis predicted his propensity to acquire various diseases. A risk assessment was performed to analyse his percentage of risk for 55 different medical conditions. A rare genetic mutation was found, which showed him to be at risk for sudden heart attack. He was also predicted to have a 23 percent risk of developing prostate cancer and a 1.4 percent risk of developing Alzheimer’s. The scientists used databases and several publications to analyse the genomic data. Even though genomic sequencing is becoming more affordable and analytical tools are becoming more reliable, ethical issues surrounding genomic analysis at a population that level remain to be addressed. But the ability to predict what diseases a person is likely to get at a future date by studying the body’s chemistry would represent one of the major triumphs of modern medical science.