Our human genome--how can it serve us well?

Abstract

Good public health, like all good medicine, rests on empirical data of high quality. If we have records of the incidence of disease, and of how this responds to interventions, we will be able to learn the best approaches for each community. Nowhere is this more true than for genetic diseases, where medical knowledge is increasing rapidly and personal issues, cultural differences and ethical dilemmas abound. Until recently, it was possible to dismiss genetics as an issue affecting a few children in rich countries. Generics looked unimportant compared to infectious diseases, high infant mortality and lack of proper sanitation. While those problems have not gone away, there are many countries (including India and China, the two largest in population) in which most people face the same medical issues as in "first world" countries -- cancer, heart disease, psychiatric disorders, diabetes, and Alzheimer's disease. With this shift, the burden of genetic disease has changed dramatically. The adult diseases listed above all have a large genetic component, often due to changes in more than one gene, which interacts with the environment in susceptible individuals. Even the consequences of cigarette smoking, one of the most serious public health issues in developing countries, are not uniform but vary with genetic susceptibility. Greater knowledge of generic factors that lead to high risk, which must be acquired for each ethnic group separately, will help public health planning and the targeting of interventions where they are most needed. Among children, once a country has lowered mortality and morbidity due to poverty, genetic diseases due to single gene mutations such as haemoglobinopathies, cystic fibrosis and muscular dystrophy consume a large proportion of paediatric resources. Of these diseases, the haemoglobinopathies (sickle cell anaemia and thalassaemia) are by far the most important internationally. There are about 200 million healthy carriers of thalassaemia or sickle cell anaemia. These carriers have a small added resistance to malaria in infancy, which is why the mutations causing haemoglobinopathies have spread throughout countries in tropical and sub-tropical regions where malaria is common. If two carriers have a child, it has a one in four chance of inheriting the mutation from both parents, causing a serious anaemia. Over 300 000 children each year are born with a severe haemoglobinopathy. With worldwide migration, these diseases are as much a feature of Europe, the United States and Australia as of the countries where they originated. In this issue, Professor Bernadette Modell, who pioneered the reorientation of clinical genetics to public health and coined the term "community genetics", puts forward evidence on the usefulness of genetic registers, in this case for thalassaemia in the United Kingdom (pp. 1006-1013). It is fascinating that even in the UK, where there is a highly organized national health system, the quality of the data depends upon the curator of the genetic register ("Personal contact is the key to success"). It is a pity that Professor Modell did not comment on this point, since it will be important when judging transferability to a country where transport may be poor and the phones may not work well. However, it is encouraging that in the UK there were no problems about confidentiality, and families were confident that the register would be used in a positive and not in a discriminatory way. …