Why study twins and what is a twin registry?
Find out the Guest Editors’ (Yoon-Mi Hur and Jeffrey M. Craig) response to these questions and more about a recent special issue in Twin Research and Human Genetics titled “Twin registries worldwide: An important resource for scientific research”
Why study twins?
Twins can provide unique and powerful opportunities to study genetic and environmental factors that make people differ in how they look, behave and how healthy they are. Monozygotic [identical] twins share all their genetic variation and dizygotic [non-identical] twin pairs, on average, share about 50% of their genetic variation. Both types of twin pairs often but not always share similar pre- and post-natal environments as well. Having twins participate in these studies helps to continue important research for common human conditions such as diseases, health, and behaviors, leading to advances in science, medicine and future potential therapies.
What is a twin registry?
A twin registry is a database of twins who have registered an interest in participating in twin research. A number of countries around the world, including Australia, UK, Denmark, the Netherlands, USA, China, Japan, and South Korea, have created large twin registries. They can have a variety of different focuses including studying particular age groups (the Arizona Twin registry studies early years whilst the Osaka University Center for Twin Study is composed of twin pairs aged 60 to 103) or ethnic groups (e.g. the Carolina African American Twin Study – CAATSA). They also vary in what they study; while the majority of studies featured in this special issue focused on behavioral, psychiatric, and cognitive phenotypes, papers also include studies on growth and development , aging, sexuality ,eyesight, and teeth.
Why publish this special issue now?
During the past 10 years, the number of twin registries has increased rapidly across the globe and we thought it timely to bring this research to the attention of our readership. In this special issue, we invited papers on twin registries and cohorts from 28 countries representing five continents.
What does the issue include?
It includes updates from registries who have previously contributed to these special issues (there was one in 2002 and another in 2006, as well as papers from new registries, including the Cuban Twin Registry (a nationwide, population-based registry consisting of approximately 58,000 pairs of twins who were identified through the National Citizen Identity Registry) and new registries in two African countries, Guinea-Bissau and Nigeria. The subjects covered in the papers include how to establish and maintain twin registries, how to accurately assess zygosity (whether a pair are identical or nonidentical), collecting biospecimens (often from tissues such as blood, saliva, or the inner cheek), and other important issues related to twin studies.
This special issue shows that over 1.5 million twins and their families are participating in twin studies worldwide.