No association between ADCYAP1R1 and post-traumatic stress disorder in two
Shun-Chiao Chang1, Pingxing Xie2,3, Raymond F. Anton4, Immaculata De Vivo5,6,
Lindsay A. Farrer7, Henry R. Kranzler8, David Oslin8, Shaun M. Purcell9,10, Andrea L.
Roberts1, Jordan W. Smoller9, Monica Uddin11, Joel Gelernter2,3,12*, Karestan C.
1 Department of Society, Human Development, and Health, Harvard School of Public
Health, Boston, MA, USA
2 Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
3 VA CT Healthcare Center, West Haven, CT, USA
4 Center for Alcohol and Drug Programs, Department of Psychiatry, Medical University
of South Carolina, Charleston, SC, USA
5 Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
6 Channing Laboratory, Brigham and Women's Hospital, Boston, MA, USA
7 Departments of Medicine, Neurology, Ophthalmology, Genetics and Genomics,
Epidemiology, and Biostatistics, Boston University Schools of Medicine and Public
Health, Boston, MA, USA
8 Department of Psychiatry, University of Pennsylvania and the Philadelphia VA Medical
Center, Philadelphia, PA, USA
9 Department of Psychiatry, Psychiatric and Neurodevelopment Genetics Unit, Center for
Genetic Research Massachusetts General Hospital and Harvard Medical School, Boston,
10 The Broad Institute, Cambridge, MA, USA
11 Center for Molecular Medicine and Genetics and Dept. of Psychiatry and Behavioral
Neurosciences, Wayne State University School of Medicine, Detroit, MI, USA.
12 Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
13Department of Epidemiology, Mailman School of Public Health, Columbia University,
New York, NY, USA.
Joel Gelernter, MD, Department of Psychiatry, Yale University School of
Medicine, VA CT Healthcare Center, 950 Campbell Avenue, 116A2, West
Haven, CT 06516. E-mail: firstname.lastname@example.org
Karestan C. Koenen, PhD, Department of Epidemiology, Mailman School of Public
Health, Columbia University, 722 West 168th Street, Room 720G, New York, NY, 10025.
Disclosures: The authors declare no conflict of interest.
Ressler et al. recently examined the pituitary adenylate cyclase-activating peptide
(PACAP) ligand/type 1 receptor (PAC1) pathway in post-traumatic stress disorder (PTSD)
in a predominantly of African American (AA) sample.1 Association analyses examining
44 single nucleotide polymorphisms (SNPs) spanning the PACAP (encoded by
ADCYAP1) and PAC1 (encoded by ADCYAP1R1) genes further identified rs2267735, a
SNP, in a putative estrogen response element (ERE) within the ADCYAP1R1 gene, which
predicted PTSD diagnosis and symptoms in females. We sought to replicate the genetic
association between rs2267735 and PTSD in two independent samples.
The first sample consisted of women from the Nurses’ Health Study II (NHSII), a
population-based prospective cohort of U.S. female nurses predominantly of European
descent. The protocol for the NHSII PTSD study has been published.2 We assessed
lifetime trauma exposure and PTSD in 2,690 women using a clinically-validated
structured diagnostic telephone interview. Rs2267735 was genotyped using a TaqMan
assay at the Channing Laboratory of Brigham and Women’s Hospital. Statistical analyses
were performed using PLINK.3
The genotyping success rate for rs2267735 was 98.2%. Genotype distribution did not
depart from Hardy–Weinberg equilibrium (HWE). To reduce potential bias by population
stratification, we restricted analyses to 2,528 women who self-reported as being
European American (EA; mean age at interview = 55 years, SD = 4.4). 584 subjects
(23.1%) had a lifetime PTSD diagnosis. In comparison, 33.0% of the 763 women in
Ressler’s study had current PTSD.1 The minor allele in Ressler et al. was C (63.6 %). In
the NHSII sample, the frequency of the C allele was 46.9 %.
The putative risk allele ‘C’ reported by Ressler1 was not significantly associated with
lifetime PTSD risk in either unadjusted or adjusted logistic regression models, whether
tested under additive, recessive, or dominant modes of inheritance. In the unadjusted
model, ‘CC’ genotype carriers showed a small but non-statistically significant increased
risk of PTSD compared to ‘CG/GG’ carriers (OR = 1.12, 95% CI = 0.90-1.40), whereas
Ressler et al reported a significantly increased risk (OR = 1.66, 95% CI = 1.32-2.09).1
Our results were similar after adjusting for age at interview, age at worst trauma, trauma
type, number of traumatic events, and lifetime depression prior to PTSD (adjusted OR
(aOR) = 1.18, 95% CI = 0.94-1.49). In contrast with the previous findings,1 rs2267735
was not associated with total number of PTSD symptoms, PTSD symptom severity or
symptom subscale scores (unadjusted p = 0.48-0.98). We also found no significant
association for current PTSD (aOR for ‘CC’ carriers = 0.94, 95% CI = 0.64-1.39),
defined as symptoms occurring within the past month, or chronic PTSD (aOR = 1.14,
95% CI = 0.84-1.55), defined as symptoms lasting more than one year. The NHS II
PTSD sample had nearly-perfect power (>99%) to detect the effect size reported by
Ressler et al: an OR of 1.66 under a dominant model with regards to the G allele.
Because rs2267735 was located within a predicted ERE,1 we further stratified the sample
by menopausal status, based on the hypothesis that the rs2267735-PTSD association may
be stronger in premenopausal women. Menopausal status and type of menopause were
assessed by biennial NHS II questionnaires. ‘CC’ genotype did not significantly increase
risk of PTSD in the premenopausal (aOR = 1.29, 95% CI = 0.96-1.74, n = 1,471) or
natural menopause group (aOR = 0.86, 95% CI = 0.43-1.73, n = 440).
The second sample contained 6,074 individuals recruited for genetic studies of substance
dependence at 5 U.S. sites.4, 5 All subjects were interviewed by trained interviewers using
the Semi-Structured Assessment for Drug Dependence and Alcoholism,6, 7 which
assessed PTSD based on DSM-IV criteria. Based on STRUCTURE8 analysis using 41
ancestry-informative markers, 3,353 participants were classified as AA (51.8% male,
mean age = 41.1 years, SD = 9.1) and 2,721 participants were classified as EA (57.7%
male, mean age = 37.7 years, SD = 11.0). 13.1% of the AAs and 15.0% of the EAs had a
lifetime diagnosis of PTSD. Rs2267735 was genotyped using a TaqMan assay at the Yale
University School of Medicine. The genotype distributions were consistent with HapMap
data and with HWE expectations in both populations. Age-adjusted logistic regression
analyses were used to examine the association between rs2267735 genotype and PTSD
risk in AA females, AA males, EA females and EA males, separately. No significant
association was observed in any of these 4 subgroups under either additive or dominant
genetic models with respect to the G allele (dominant model: AA female: OR = 1.13,
95% CI = 0.86-1.50; AA male: OR = 0.99, 95% CI = 0.73-1.32; EA female: OR = 1.07,
95% CI = 0.76-1.50; EA male: OR = 0.93, 95% CI = 0.65-1.32). Both AA and EA female
samples had good power (93% and 77%, respectively) to detect an effect of the size
reported by Ressler et al. In addition, there was no evidence of association when
restricting the analysis to AA females younger than 45 years (n = 1198, of which 186 had
PTSD) who are likely to be pre-menopausal using an additive or dominant model
(dominant model: OR = 1.29, 95% CI = 0.93-1.78).
In summary, we were unable to replicate the association between rs2267735 and PTSD in
either AA or EA females in these two large independent samples. Our findings do not,
however, exclude the possibility that the PACAP-PAC1 receptor pathway plays a role in
the production of PTSD. Our replication samples differ principally from Ressler’s sample
on three grounds: sample selection, demographic characteristics, and participant’s social
context. Ressler’s sample was recruited from patients in medical clinics and comprised of
relatively young (mean age = 39.6 years), low-income, largely unemployed, African
Americans, highly trauma exposed, inner city residents. In contrast, the NHSII sample
was population-based, older European Americans with much higher income and
education. The Yale samples comprised of both AA and EA young substance dependence
cases and unaffected controls, related or unrelated, who participated in the study focused
on the genetics of substance dependence (mean age = 39 years).
Some might argue that a “true” genetic effect would be observed across samples
regardless of these differences. However, as we note elsewhere, animal models and
human correlational studies suggest both individual-level and social environmental
factors modify genetic effects.9, 10 Further research is needed to understand how selection
factors, demographic characteristics and social context influence the role of the PACAP-
PAC1 receptor pathway in PTSD.
1. Ressler KJ, Mercer KB, Bradley B, Jovanovic T, Mahan A, Kerley K et al.
Nature 2011; 470(7335): 492-497.
2. Koenen KC, DeVivo I, Rich-Edwards J, Smoller JW, Wright RJ, Purcell SM.
BMC Psychiatry 2009; 9: 29.
3. Purcell S, Neale B, Todd-Brown K, Thomas L, Ferreira MA, Bender D et al. Am
J Hum Genet 2007; 81(3): 559-575.
4. Gelernter J, Kranzler HR, Panhuysen C, Weiss RD, Brady K, Poling J et al.
Dense genomewide linkage scan for alcohol dependence in African Americans:
significant linkage on chromosome 10. Biol Psychiatry 2009; 65(2): 111-115.
5. Gelernter J, Panhuysen C, Wilcox M, Hesselbrock V, Rounsaville B, Poling J et
al. Am J Hum Genet 2006; 78(5): 759-769.
6. Pierucci-Lagha A, Gelernter J, Chan G, Arias A, Cubells JF, Farrer L et al. Drug
Alcohol Depend 2007; 91(1): 85-90.
7. Pierucci-Lagha A, Gelernter J, Feinn R, Cubells JF, Pearson D, Pollastri A et al.
Drug Alcohol Depend 2005; 80(3): 303-312.
Pritchard JK, Rosenberg NA. Am J Hum Genet 1999; 65(1): 220-228.
Koenen KC, Galea S. JAMA 2009; 302(17): 1859; author reply 1861-1852.
Koenen KC, Uddin M, Amstadter AB, Galea S. Int J Clin Pract; 64(11): 1489-