Vietnam Era Twin Registry Biospecimen Repository

The Vietnam Era Twin (VET) Registry maintains a repository of biological specimens obtained from Registry members. The VET Registry Biospecimen Repository includes DNA, plasma, and serum samples obtained from selected VET Registry members. As the VET Registry is a national resource for studies investigating genetic and non-genetic influences on health and disease in middle age men, this enhances the value of the information collected from VET Registry members to the research community.

The VET Registry has developed a general system of protocols for the collection and storage of biological specimens that assures confidentiality for all participants. The biological specimens currently in use are stored at the R&D Core Laboratory at the VA Puget Sound Health Care System (VAPSHCS) in Seattle, WA.  The R&D Core Laboratory performs DNA extraction procedures and separates out DNA, plasma, and serum for testing and storage.  It is important to note that Core Laboratory staff has absolutely no phenotypic (non-genetic) information about VET Registry members, as the lab is completely blinded to the identity, disease characteristics, and any other research data collected from VET Registry members. The Massachusetts Veterans Epidemiology Research and Information Center (MAVERIC) Core Laboratory is located at the VA Boston Health Care System in Boston, MA, and serves as the long-term storage site for the VET Registry Biospecimen Repository.

Before a VET Registry member decides whether to participate in the Biospecimen Repository, the procedures, confidentiality safeguards, and potential risks are explained in great detail. To be able to accommodate the wishes of members, a so-called layered consent process is used which allows members to choose from several options with regard to how their biological specimen will be used in current or future research studies. Such options may include: 1) not having their samples used for any testing beyond the immediate goals of the study; 2) allowing for future testing of their samples restricted to the study for which they provided the sample; or 3) allowing unrestricted future research use of their samples. Members are informed that any future use of their samples would have to be approved by the VET Registry, in addition to an independent ethics committee that protects the rights and welfare of research subjects, this board is more commonly known as an Institutional Review Board or IRB. Confidentiality safeguards include assigning code numbers, as opposed to name or other personal information, on all biological specimens.

Zygosity Testing

The accuracy of DNA testing makes it the best method for determining zygosity, identical (monozygotic) versus fraternal (non-identical or dizygotic), in VET Registry twin members. When there are no differences found in the genes being compared in a test of zygosity, the chances are less than 1 in 100, the twins are monozygotic (identical), in other words, the twins are more than 99% certain to be dizygotic (fraternal).The use of DNA for zygosity testing is only performed when both members of a twin pair agree to the testing. Therefore twins are explicitly told that this aspect of the test requires both members to consent. If one member of the pair is willing while the other is not, then the testing cannot be performed. If both members of the twin pair wish to be informed of the results of zygosity testing, the VET Registry will provide this to them by mail after testing is complete.  Test results may not be available for up to year since testing is done in batches.  The vast majority of twins already have an excellent grasp of their own zygosity and studies have indicated that self-assessment is over 95% accurate. In most cases the twins in the VET Registry already know their zygosity, but there will be some twins who either do not know or have incorrectly assessed their zygosity.

Other Genetic Testing

Genetic testing for specific genes will not necessarily involve providing the participants with test results. This is because many of the genes identified by investigators in genetic analysis have unknown or uncertain consequences for the future health of the individual. The decision to disclose genetic information to study subjects is made based on the general guidelines outlined in the National Bioethical Advisory Committee (NBAC) report, which indicates that all of the following conditions should apply before disclosure to study participants:

1. findings are scientifically valid and confirmed, and
2. findings have significant implications for the subject's health, and
3. a course of action or treatment is available, and
4. appropriate medical advice or referral is provided.

Each study involving genetic testing beyond zygosity testing will be reviewed for the following conditions and decisions will be made accordingly.