A genealogy of the United States has been record-linked to National Veteran’s Health Administration (VHA) patient data to allow non-identifiable analysis of familial clustering. This genealogy, including over 70 million individuals linked to over 1 million VHA patients, is the largest such combined resource reported. Analysis of familial clustering among VHA patients diagnosed with post-traumatic stress disorder (PTSD) allowed a test of the hypothesis of an inherited contribution to PTSD.

PTSD is associated strongly with military service and extended familial clustering data have not previously been presented. PTSD-affected VHA patients with genealogy data were identified by presence of an ICD diagnosis code in the VHA medical record in at least 2 different years. The Genealogical Index of Familiality (GIF) method was used to compare the average relatedness of VHA patients diagnosed with PTSD with their expected average relatedness, estimated from randomly selected sets of matched linked VHA patient controls. Relative risks for PTSD were estimated in first-degree, second-degree, and third-degree relatives of PTSD patients who were also VHA patients, using sex and age-matched rates for PTSD estimated from all linked VHA patients. statistically-significant excess pairwise relatedness, and statistically-significantly elevated risk for PTSD in first-degree, second-degree, and third-degree relatives was observed; multiple high-risk extended PTSD pedigrees were identified.

The analysis provides evidence for excess familial clustering of PTSD and identified high-risk PTSD pedigrees. These results support an inherited contribution to PTSD predisposition and identify a powerful resource of high-risk PTSD pedigrees for predisposition gene identification.

[Keywords: genealogy, PTSD, relative risk, high-risk pedigree, US veterans genealogy]

…US Veterans Genealogy: Genealogical data for over 70 million individuals gathered from public sources have been linked into an initial genealogy that represents 20–25% of the population of the United States (Cannon-Albright et al 2013_11ya, Cannon-Albright et al 2018). The demographic data for 13 million Veterans registered by the Veterans Health Administration (VHA) System was evaluated to record-link to this current US genealogy data using specific software tools included in GenMergeDB, which has been used to create, and link records to, multiple genealogical resources for decades (Cannon-Albright et al 2018). ~1 million of the VHA patients were linked to an unique individual in the genealogy. After this initial record linking, no individual identifying data was used; informed consent was waived. A total of 284,382 of these linked VHA patients have extensive genealogy data, including at least 6 of their 14 immediate ancestors (both parents, and all 4 grandparents); many have much more genealogy data. This study analyzed these 284,382 VHA patients and their over 3 million ancestors, providing sufficient numbers of both close and distant relatives for appropriate genetic analysis. Access to over 300 million coded diagnoses or medical procedures linked to the 1 million VHA patients with linked genealogy (who remained unidentified) was approved by the Institutional Review Board and an oversight committee for the VHA resource.

The US Veterans Genealogy Resource currently includes VHA patients born in every state of the US. Among the ~1 million VHA patients with any linked genealogy data, 67,926 (6.5%) were female. We observed a similar percentage of among those 284,382 Veterans who link to an individual with at least 6 ancestors in the US Veterans Genealogy (4.5%). There are patients with genealogy identified in all 23 VHA Veterans Integrated Service Networks in 2017 (VISNs or local VHA health care providers) across the US ~81% of the linked VHA patients have VISN data, and among those, the largest numbers of linked VHA patients were in VISN 8 (Florida, Puerto Rico, US Virgin Islands; n = 71,238), VISN 23 (Illinois, Iowa, Minnesota, Nebraska, North and South Dakota; n = 64,763), and VISN 16 (Arkansas, Louisiana, Mississippi, Oklahoma, Texas; n = 59,142). The birth years for VHA patients linked to genealogy data ranged from the 1890s to the 1990s. There was a large peak of births for the 972,306 linked males for the birth years 1921^–₉1930_94ya (24% of all linked males born in this range) and a peak for the 67,926 linked females for birth years 1951^–₉1960_64ya (20% of all linked females born in this range).

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