Establishing a child and adolescent twin register for research and capacity building on the aetiology of mental illness in Sri Lanka and other LMIC The Medical Research Council is offering a one year grant opportunity to lay the grounds for future large scale research to study mental health issues in low and middle income countries (LMICs). This will build on existing UK-LMIC partnerships and initiate new ones.   Through this grant, we plan to take the initial steps for such research, and to establish a register of infant, child and adolescent twins, and of mothers pregnant with twins, in Sri Lanka (the capital Colombo in the Western province and Vavuniya in the Northern Province). Once the register is developed, our research will start exploring what causes mental illness; the impact of early brain development and the role of genetic, developmental, environmental, social and cultural contributions on the origin of mental disease. Research on twins has several advantages over studying non-twin people since it is possible to study the similarities and differences of identical and non-identical twins in order to understand the relative contribution of genetics and the environment.   We believe that as a result of the initial work undertaken during the first year, we will be able to establish a large register of young twins, some with linked data from their parents via an existing adult twin register, and identify initial data from routine records on children's health and education. Being included on the register does not automatically mean involvement in research. Future research projects will need separate consent and ethics approval from the country of origin of the research proposal and SL.  Our long term vision is to increase the amount of research that can have an influence on health and social care in SL and South Asia. The main partner in this venture is the Institute for Research and Development (IRD SL), which has already established one of the few large functioning population-based adult twin registers, successfully carried out two rounds of published studies, recruited a matched non-twin sample and established a biobank and genetic laboratory. We have also partnered with three South Asian institutions: Independent University of Bangladesh, Health Services Academy-Islamabad, Pakistan, and All India Institute of Medical Sciences.  The UK partners are Keele University, Kings College London, and University of Bristol. We will work towards establishing a virtual centre of excellence on cohort studies (following up a large group of persons to do research).    The three main pillars of the initiative are: (i) high quality research, (ii) ethics, (iii) patient and public involvement and engagement (PPIE).  Our team includes world leading experts in twin research, mental health, research methods, ethics, PPIE, and grant development. Increasing the skills of junior academics across the partnership will develop future research leaders and essential skills in all three pillars. We will bring together senior researchers from the partner organisations and form the planning and coordinating units, the steering committee, and the research, ethics and PPIE expert groups to organise these activities. Strengthening the ethics framework within the initiative is very important and we will revise the guidelines developed previously by the IRD.  PPIE is a novel concept to South Asia. Evidence from the UK demonstrates that the quality of research is better and the likelihood of successful recruitment and implementation of the findings is improved when patients and the public are involved in research. We aim to establish a culture of PPIE in Sri Lanka, working with both academic colleagues and lay members; in this instance specifically with twins and their parents.          We plan to develop at least two proposals within the year for further in-depth research and funding. We will decide on the key research questions guided by the research gaps, data gathered during the first year and discussion with patients and public. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.