New methods of collecting DNA using saliva samples could help enhance cohort datasets with valuable biological information, a new study suggests.
Researchers at the Institute of Education‘s Centre for Longitudinal Studies (CLS) and Ipsos MORI tested the viability of collecting saliva from 11-year-olds and their natural mothers and fathers. They found that most children and their parents were willing to consent to the procedure when provided with clear information on how and why their samples were being taken.
This was the first attempt in the UK to collect saliva samples for DNA extraction from children in a home setting. It is also thought to be the first time genetic material has been obtained from natural fathers, as well as natural mothers and children, in a study of this kind.
“There has been a substantial increase in recent years in collecting biological data on social surveys,” explain the authors. “This has been driven by growing scientific interest in the interplay between social and biological factors in explaining human behaviour.”
Lisa Calderwood, Senior Survey Manager at CLS, and Nickie Rose, Research Director at Ipsos MORI, led this work in order to explore possibilities for future surveys of the Millennium Cohort Study (MCS), which follows 19,000 children born across the UK in 2000-01. Longitudinal studies such as the MCS cover a wide range of topics, including parenting, behaviour, cognitive development, educational attainment, employment, income and housing. Biological samples, such as blood and saliva, can be used to extract DNA information, which can then be used to determine the relationship between genetics and social outcomes.
There are ethical challenges when collecting biological samples, particularly when dealing with children. This study required informed consent from both the 11-year-olds and their legal guardians. Participants in this study were given leaflets explaining what genes are, why it is important to research them, what the procedure involved, and what their saliva samples would and would not be used for. The participants were then given the opportunity to ask the interviewer questions and raise concerns. Over 70 per cent of mothers, fathers and children ultimately consented to giving saliva samples.
The authors recommended that future surveys always provide clear and detailed information to participants, and in particular give reassurances that their DNA would not be linked to government records or any other database. Provided adequate training is given to interviewers, and sufficient information given to participants, the authors see saliva samples as a viable way of extracting DNA to enhance cohort data sets.
Collecting biological samples in a large-scale survey can also be costly. Previous methods of obtaining DNA have required respondents to give a blood sample, which can only be done by nurses or other trained medical staff. However, improved technology has made it possible to obtain participants’ DNA by much less invasive means and without requiring interviewers with medical training. In this study, participants were asked to spit into a tube, which was then passed back to the interviewer to be sealed and stored. Interviewers were given training in how to carry out the procedure, but they did not require medical qualifications. Advances in genetic research have made it possible to then extract DNA from the saliva samples when back at the lab.
‘Collecting saliva samples for DNA extraction from children and parents: Evidence from the UK Millennium Cohort Study’ by Lisa Calderwood and Nickie Rose