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VA Cooperative Studies Program (CSP)

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CSP #256: Vietnam-Era Twin (VET) Registry & Repository


Investigator Access

What's available

  • Participant contact information: Names and contact information of participants recruited for the VET Registry. (PDF format - scanned copy of permission to contact form)
  • Research data: Coded individual participant data collected from Registry-wide surveys, studies utilizing the Registry resources, and Registry maintenance procedures. (SAS, Stata, SPSS, Excel, CSV, and text file formats)
  • Biospecimens: Coded DNA, plasma, and serum samples from 1,800 participants

Available documentation 

Dates data are available

Currently available, no end date

Access criteria

Investigators associated with VA or non-VA nonprofit, academic, or research institutions can request access by following these steps

Requests are reviewed for scientific merit and ethical standards. If the request involves human subjects research, access is contingent upon approval by an Institutional Review Board (IRB) and, if VA research, by a VA Research and Development (R&D) Committee. Before resources are transferred, requestors may be required to sign a VA data use agreement or Material Transfer Agreement (MTA). Requestors must be fully compliant with any applicable VA data security, privacy, confidentiality, and human subjects requirements.

 Study Characteristics


The VET Registry is one of the largest national samples of adult twins in the United States. It includes data from more than 30 studies and biospecimens from over 1,800 individuals.  

The goals of the VET Registry are supporting and promoting scientific research, safeguarding the members and resources for future research, and maintaining a secure and updated database and biospecimen repository, while treating its members with respect and maintaining their confidentiality.

Era of Service



Vietnam-era identical (monozygotic) and fraternal (dizygotic) male twins who served in the military from 1964-1975 (Vietnam conflict). The Registry also includes a selected population of twin offspring and the offspring’s mother.

Study Design 

Prospective cohort study

Time Period 

1983 - present




Twins: 14,738 (initial pool identified as twin pairs); ~10,500 (currently alive and not withdrawn, as of June 2018)
Offspring: ~2,200 
Offspring's mothers: ~1,200
Major VET Registry-wide data collection efforts:

  • 1987 Survey of Health: N=10,979
  • 1992 National Heart, Lung, and Blood Institute (NHLBI) Survey: N=8,855
  • 1992 Harvard Drug Study: N=8,169
  • 1999 Male Health Study: N=5,631
  • 2010 Veteran Health Study: N=7,384 (mail survey), N=6,004 (telephone interview)

Response Rate

Participation rates of VET Registry wide surveys: 

  • 1987 Survey of Health: 75%
  • 1992 NHLBI Survey: 74%
  • 1992 Harvard Drug Study: 79.7%
  • 1999 Male Health Survey: 49.8%
  • 2010 Veteran Health Study: 57% (mailed survey), 45% (telephone interview)

Recruitment Method

The VET Registry was formed through a search of computerized records maintained by the Department of Defense and supplemented by the VA database files. Registry members were mailed information sheets and given the opportunity to consent to or withdraw from participating in the registry.  


Varies depending on type of data collection effort that the Registry member is enrolled in

Data Collected

Registry resources include:

  • Individually identifying information: name and contact information
  • Data repository: health-related information data (e.g., posttraumatic stress disorder (PTSD), body mass index, diabetes, cardiovascular disease, depression, and substance use); data extracted from public or private databases; genetic data generated from biospecimens samples
  • Biospecimens repository: DNA, plasma, and serum collected from samples of blood, saliva, urine, and buccal scraping

Data Collection Method

In-person assessments and examinations, in-person and telephone interviews, in-person focus groups, biospecimen collection, mail surveys 

Funding Sources 

VA Cooperative Studies Program (CSP)

Contact   /   1-800-329-8387, ext. 61964

Selected Publications

Eisen S, Neuman R, Goldberg J, Rice J, True W. Determining zygosity in the Vietnam Era Twin Registry: an approach using questionnaires. Clin Genet. 1989 Jun;35(6):423-32.

Goldberg J, Curran B, Vitek ME, Henderson WG, Boyko EJ. The Vietnam Era Twin Registry. Twin Res. 2002 Oct;5(5):476-81.

Forsberg CW, Goldberg J, Sporleder J, Smith NL. Determining zygosity in the Vietnam era twin registry: an update. Twin Res Hum Genet. 2010 Oct;13(5):461-4.

Tsai M, Mori AM, Forsberg CW, Waiss N, Sporleder JL, Smith NL, Goldberg J. The Vietnam Era Twin Registry: A Quarter Century of Progress. Twin Res Hum Genet. 2013 Feb;16(1):429-36. Epub 2012 Nov 26.

Complete list of publications using VET Registry 

More Information