Twin registry
A twin registry is a
Investigative use
The use of twins can improve the statistical power of a genetic study by reducing the amount of genetic and/or environmental variability.
Where maintained
Some twin registries seek to cover all twins in an entire country,
Other twin registries cover a more limited geographic scope and are maintained by researchers at academic institutions, such as the
Limitations
Many twin registries depend on the voluntary participation of twins – that is, participation in these twin registries is not compulsory, and twins must voluntarily elect whether or not to register with a twin registry (and later, whether to participate in research projects). This characteristic limitation of many twin registries leads to standard issues known as "recruitment bias" or "volunteer bias".[9] Recruitment biases include an over-inclusion of twins who share similar characteristics,[4] and over-inclusion of identical twins and female twins:[10]
- "[T]his recruitment bias ... results in ... overestimation of the true heritability of the trait under study."[10]
Twin registries use a number of strategies to try to reduce the risk of recruitment bias. Some twin registries are "mandatory" - that is, for example, under the public health laws of Norway, all births of twins since 1967 have been recorded in a twin registry maintained by the Norwegian government.[4] By comparison, enlisting with the Australian Twin Registry is voluntary.[11] While the twin registry in Sri Lanka is based on volunteer twins, that twin registry has made extensive out-reach efforts, such as examining hospital birth records, and then making multiple follow-up efforts (including in-person visits) to find the twins and have them (or their parents) agree to be registered.[12]
Footnotes
- ^ a b c d NIEHS Twin Registry accessed 2013-06-14. (Some of the text in this article is a close paraphrase of the material on this website maintained by the U.S. Federal Government, and which is a document in the public domain.)
- ^ a b Swedish Twin Registry accessed 2013-06-14
- ^ Danish Twin Registry accessed 2013-06-14
- ^ a b c Tambs, Rønning et al.; "The Norwegian Institute of Public Health Twin Study of Mental Health: Examining Recruitment and Attrition Bias" Twin Res Hum Genet. 2009 April; 12(2): 158–168. doi: 10.1375/twin.12.2.158. Accessed 2013-06-14
- ^ Australian Twin Registry accessed 2013-06-14
- ^ Sri Lankan Twin Registry accessed 2015-05-15
- ^ U.K. Twin Registry accessed 2013-06-14
- ^ Washington State Twin Registry accessed 2016-07-11
- ^ D. T. Lykken, M. McGue, A. Tellegen; "Recruitment bias in twin research: The rule of two-thirds reconsidered"; Behavior Genetics:vol. 17, no. 4, pp. 343-362, 1987. DOI: 10.1007/BF01068136 Accessed 2013-06-14
- ^ a b D. T. Lykken, A. Tellegen & R. DeRubeis; "Volunteer bias in twin research: The rule of two‐thirds" Biodemography and Social Biology:Volume 25, Issue 1, 1978. Accessed 2013-06-14
- ^ Australian Twin Registry registration "With over 70,000 members the ATR has become the largest volunteer registry of multiples in the world. Nevertheless, this still only represents about 10% – 15% of twins in Australia and we need more recruits!" Accessed 2013-06-16.
- ^ Siribaddana SH, Siriwardane WD, et al. "Update from Sri Lankan Twin Registry" Twin Res Hum Genet. 2006 Dec;9(6):868-74.