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By JULIE MINDA

Genomic information that could lead to new insights into some of humanity's most difficult-to-understand diseases could be lurking in the most unlikely of places: Sioux Falls, S.D.

A twin register launched in the spring at the Avera Institute for Human Genetics in Sioux Falls is collecting the DNA and health history of twins and other multiples around the world — as well as that of their family members — and is offering the related genomic information to researchers. Those researchers will use the data to try to understand the interplay of genetics and environment in the development and progression of disease.

"Determining the genes that are responsible for complex diseases and those which kill most of us is a very, very important question of course for mankind; and the use of twins is a critical component in that," says Gareth Davies, chief scientific officer and scientific director at the Avera Institute.

According to Avera's twin registry website, identical twins share 100 percent of their DNA, while fraternal twins usually share 50 percent. The twin studies will attempt to determine what factors are at work when one twin gets a disease and the other doesn't.

"The twin model, as it is called, is just such an important part of genetics," he says.

Collaborative research
Founded in 2006, the Avera Institute specializes in DNA analysis and personalized medicine. Its research team is involved in both clinical analysis and research, including in pharmacogenomics, or the study of how people's genetic makeup may influence how they respond to medications. The institute has a molecular genetics laboratory capable of sequencing, genotyping and phenotyping DNA. Sequencing involves determining the exact order of the elements of DNA; genotyping involves analyzing the DNA; and phenotyping involves studying how people's genes interact with their environment.

Identical twins Sayers, left, and Kamper — along with their parents, Craig McCarthy and Rebecca Amble — help to launch the twin register at the Avera Institute for Human Genetics in the spring.

The institute has been performing DNA analysis for researchers and research organizations around the world since its founding. The launch of the twin register expands the institute's capabilities. According to the International Society for Twin Studies, there are more than 30 twin registries in 20 countries. There are nine in the U.S., not including the Avera Twin Register. Davies says some registers are large, some small, some collect a broad base of samples, some specialize in a particular population.

Small effects, big science
Davies says organizations with twin registers share the de-identified genetic information they glean from twins' DNA, at no cost, with researchers studying the genetic underpinnings of a myriad of conditions. This collaborative research approach is necessary because individual repositories do not have large enough sample sizes to be valid for the study of complex diseases.

This is especially true for researchers studying diseases involving multiple genes which produce small, but cumulative effects. Davies explains that there are diseases that result from multiple genes interacting with one another and with a person's environment, which includes the person's lifestyle choices. Heart disease, cancer, obesity, stroke and diabetes are diseases that can involve genes of small effect.

Only by studying the genetic data of tens of thousands of people at once can researchers gain valid insights into such conditions. Davies refers to such mass genomic research projects as "big science."

A resource from the institute explains how the "power of twin data" can work: Researchers in one study combined twin data from several registries to determine that attention deficit/hyperactivity disorder is about 60 percent to 80 percent genetic and about 20 percent to 40 percent environmental. Davies says the Avera Institute was involved in that ADHD study.

DNA swab
The Avera Institute announced its twin register in May and has been relying on word of mouth, social media and news media coverage to attract participants' interest, according to Julie Kittelsrud, a nurse practitioner who coordinates Avera's twin register.

The institute welcomes for its register both fraternal and identical twins, triplets and other multiples as well as their family members. The multiples and their immediate family members can be from anywhere in the world, but most so far have been from South Dakota, Minnesota, Iowa and Nebraska. People of any age, ethnicity or gender are eligible. The institute will accept samples for one twin, even if the other is not participating in the register.

Area residents interested in taking part visit the Sioux Falls institute. Staff explain the register to them and describe what's required of participants. Those who go forward fill out a health history and give a saliva sample for DNA analysis.

People who do not live near Sioux Falls can go through the process over the phone and by mail.

Already about 500 people have joined the register. They get no payment.

Longitudinal study
Davies and Kittelsrud say the institute will maintain contact with register participants. About annually, participants will fill out new questionnaires to update the institute on their health status. This will enable researchers who use the data to get a longitudinal look at the subjects' conditions.

Davies says the institute also likely will request new cheek swabs at some time in the future from some or all register participants. He says while a person's DNA does not change, its structure can change, and that can influence how genes are expressed. He explains that the study of epigenetics involves learning how certain behaviors can affect how genes are expressed. For example, smoking or eating unhealthy foods may have an impact on a person's DNA structure and thus may impact how genes are expressed.

Learning which genes are affected by particular environmental influences, and in what way, is critical information to have, says Davies. New DNA samples from the register's participants may provide clues on epigenetics to researchers, he says.

Leading edge
Dr. Dave Kapaska is president and chief executive of Avera McKennan Hospital & University Health Center in Sioux Falls. He said in a statement announcing the twin register that the type of research that the institute is conducting and advancing through the twin register "provides the foundation for the future of medicine."

The twin register data will help scientists gain greater knowledge of genetic influences on health, which in turn could lead to more accurate diagnoses, the development of better treatments and the prevention of disease, according to information from Avera Health, the parent of the institute and hospital.

Kapaska says, "We're only beginning to scratch the surface of the potential that is waiting to be discovered."

Copyright © 2016 by the Catholic Health Association of the United States
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