1.  The ALSPAC study is designed to look at the ways in which different aspects of the environment impact on the development and health of the child and parents, and the ways in which such influences are affected by genetic susceptibility.

  The study was designed therefore to collect blood samples for extraction of DNA from the very beginning. Women who were pregnant with an expected date of delivery between 1 April 1991 and 31 December 1992 were enrolled in the study if they were resident in Avon. The bulk of the information is collected from questionnaires completed by the parents, and more recently the children, as well as medical and other record extraction. From the age of seven years onwards children have been invited to visit the study and undertake a number of different tests on a one to one basis.

  A brochure outlining the types of data to be collected was given to mothers at the very start of the study and this included information on the analysis of DNA. Women were told that being part of the study was purely optional, and that they could withdraw at any time they wanted. At the same time they were informed that biological samples would only be analysed with their signed permission.

  The study is based within the University of Bristol and all data and biological samples belong to the University. It is governed by a Scientific Advisory Committee which is in turn advised by an Ethics and Law Sub-committee, a Genetic Advisory Committee, a Cognitive, Educational and Social Development Advisory Committee and a Biomarker Advisory Group.

  The overall aim of the study is to continue following up the children and their parents, monitoring the changes in the environment (which we define as all aspects of exposure whether physical, psychological or social) throughout the rest of their lives.

  Full details of the study can be found on the study website at www.ich.bristol.ac.uk/alspac.html.

  2.  Funding for this study has come from a wide variety of sources including the Medical Research Council, UK Government Departments such as MAFF, Department of Health, Department for Education and the Health and Safety Executive. Other sources of funds include Medical Research Charities such as the Wellcome Trust, the National Asthma Campaign, American sources such as the National Institutes of Health and the March of Dimes charity. Commercial funding has been provided to enable the study to look at the safety of specific products such as Coca Cola or electric blankets. Such projects are always undertaken on the understanding that the study has the right to publish the results regardless of what is found.

  3.  Biological samples were obtained from the mother during pregnancy by asking community midwives to take an extra sample of blood for the study at each time point at which they were taking blood from the pregnant woman. This blood sample was sent to the study laboratory, and in addition the study went to the local laboratories and acquired any blood from the women that was left over after clinical assays had been undertaken. At the time of delivery a sample of blood from the umbilical cord was collected specifically for the study, a piece of the cord was frozen and the placenta was kept in formalin. As already indicated, we have promised mothers that we would not analyse these samples without their signed permission. There are to date 14,000 women who have signed permission forms out of a total sample of 14,500.

  DNA is being extracted from the mother's blood and the child's blood. This provides a variable amount of DNA, which will certainly be insufficient for the number of assays that will be requested over time.

  With the human genome project being able to identify many hundreds of thousands of genes, there is more pressure to have an extensive stock of DNA. It has therefore been decided to investigate the possibilities of immortalised cell lines on fresh samples of blood to be taken from parents and their children. Whilst this has received the approval of the ALSPAC Ethics Committee, it has yet to go through the local NHS Ethics Committees. In approaching parents for permission to create immortalised cell lines, the option always to be able to opt out will be emphasized. No pressure will be put on parents or the children to take part in this aspect of the study, but it is hoped that a large proportion of the families will want to do so.

  4.  The consent forms signed by the mother in respect of the biological samples have always stipulated that no results from any of the assays to be carried out would be linked back to the name of either the mother or child. We occasionally stipulate at the time of taking the sample that we are going to carry out a particular assay and feed the results back. In such an instance we carry out the assay prior to complete anonymisation of the sample. For all genetic assays, no feedback of results to the family will be undertaken. We always present specific problems to the ALSPAC Ethics Committee for discussion.

  Collaboration with scientists in a variety of different fields is important. This is carried out with due care, taking full account of the confidential and sensitive nature of the data involved. A balance has to be carefully made between making the information as freely available as possible to the research community in general, and preserving the confidentiality of the study. Up until now, geneticists have received aliquots of DNA from a group of ALSPAC participants, which they have genotyped and the data has then been linked back into the overall database. Unused DNA is returned to the study centre. Statistical analysis of such data, linked to the other information held on these parents and children is then carried out within the ALSPAC offices, either with the ALSPAC statisticians carrying out the statistical analyses under the guidance of the geneticists, or vice versa. In this way it is intended that the confidentiality and inability to link genetic information with other identifying details will be preserved.

  The Scientific Advisory Committee has overall control of which projects are undertaken. For this they take advice from experts in the field. This safeguards the scientific integrity of the projects carried out.

Professor Jean Golding, Scientific and Executive Director of the ALSPAC Study, University of Bristol.
Professor Marcus Pembrey, Director of Genetics within the ALSPAC Study.
Professor Michael Furmston, Professor of Law and Chair of the Ethics and Law Sub-Committee.