Mismatch - Our modern lifestyle and the chronic disease timebomb

The rapid rate of urbanisation, with its accompanying changes in diet and physical acitivity, has meant that our genes - selected and tuned over thousands of years of our evolution - have got left behind.

Speaking at the BA Festival of Science in Liverpool, Professor Mark Hanson, Director of the Institute of Developmental Sciences at the University of Southampton, and Peter Gluckman from the University of Auckland explained that environmental factors during early development, including the mother’s diet, her age, whether she is overweight, stressed, a smoker and how much exercise she does, could influence her child’s vulnerability to diseases such as obesity, diabetes and heart disease in later life, and could cause problems such as infertility or early puberty and some forms of cancer. It could even be to blame for some mental health diseases.

Although we inherit our genetic information from our parents, environmental factors affect the development of the fetus in the womb by tweaking the inherited genes to ‘switch’ certain ones on or off. Professor Hanson explains: “If the genetic code is like the text of a document, environmental factors can act to change the message it conveys, just as if someone has come along and altered the grammar, highlighted some words and pasted some others out. The meaning changes totally. For genes this is known as an epigenetic process and it alters the way genes are expressed or read, just like the text of the document.”

This epigenetic process operates in all babies and works to match how they develop to suit the world in which they will live. But if the signals from the mother – from her diet, for example – are not accurate, or if the environment changes in her child’s lifetime, the baby may be born poorly adapted to deal with its surroundings – hence the term ‘mismatch’.

Mismatch contributes to the epidemic of conditions such as obesity in richer developed countries but Professor Hanson and his colleagues are very concerned that it is also becoming a major issue in developing countries where people have to adapt to nutritional changes very fast. Professor Hanson says: “We are now seeing the epidemic of diabetes and cardiovascular disease in parts of India which have changed fast, and it affects people at a much earlier age and who are not fat by Western standards. Their diet was traditionally poor and exercise levels high – but as rural people move into cities they are increasingly mismatched. The economic consequences of this for developing countries such as India, China and in Africa will be horrendous.”

But the situation is not as doom-laden or deterministic as it would be if it were all down to inherited genes. Recent research into the underlying processes of epigenetics has revealed that there is potential for switching back the changes leading to mismatch, if they are detected in time.

The team are now trying to calculate the cost to human health of this mismatch in developed and developing countries. Clearly, just focusing on adult lifestyle interventions to solve the problems of chronic disease will not be enough. The hope is that if epigenetic ‘markers’ can be identified, those people most vulnerable to mismatch can be screened and appropriate action taken before chronic diseases develop.