Twin registry

A twin registry is a database of information about both identical twins and fraternal twins, which is often maintained by an academic institution, such as a university, or by other research institutions.

The use of twins can improve the statistical power of a genetic study by reducing the amount of genetic and/or environmental variability. "Identical twins" (monozygotic (MZ) twins) share virtually all their genes with each other, and "fraternal twins" (dizygotic (DZ) twins), on average, share about 50% of their genes with each other (about the same amount of sharing as non-twin siblings). Both types of twin pairs in twin registries almost always share similar prenatal and early childhood environments as well. By determining what are called "concordance" rates for a disease or trait among identical and fraternal twin pairs, researchers can estimate whether contributing factors for that disease or trait are more likely to be hereditary, environmental, or some combination of these. A concordance rate is a statistical measure of probability - if one twin has a specific trait or disease, what is the probability that the other twin has (or will develop) that same trait or disease. In addition, with structural equation modeling and multivariate analyses of twin data, researchers can offer estimates of the extent to which allelic variants and environment may influence phenotypic traits.

Some twin registries seek to cover all twins in an entire country, including Sweden,Denmark,Norway,Finland, Australia,Sri Lanka and the United Kingdom. The Swedish Twin Registry is the largest twin database in the world, with approximately 85,000 twin pairs.

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