Table 4.

Genetic evidence.

Reference	Sample	Psychological Assessment	Biological Parameters	Main Findings
Dunn, 2014 [48]	205 low-income non-Hispanic Black people exposed to Hurricane Katrina; (F = 197, M = 8; mean age = 25.82 ± 4.39 years)	Specifically tailored scale to measure Hurricane Katrina exposure; PTGI; IESR	There was evaluated the modification in 7 genes: BDNF (rs6265, chromosome 11p14), CACNA1C (rs1006737, chromosome 12p13), CRHR1 (rs12944712; chromosome 17q21), FKBP5 (rs1360780, rs9296158, and rs9470080, chromosome 6p21), OXTR (rs53576 and rs2254298, chromosome 3p25), RGS2 (rs4606, chromosome 1q31), SLC6A4 (variable number tandem repeat VNTR and rs25531, chromosome 17.q11–17.q12).	Results showed a significant positive association between PTGI total score and the presence of homozygotes rs4606 variant of RGS2 gene, which was later confirmed after correcting for multiple testing and appeared mostly driven by a GxE interaction, rather than only by a genetic effect. Among participants with low levels of Hurricane exposure, minor allele (G allele) homozygous subjects for rs4606 reported lower total scores on PTGI, while the same variant was associated with higher total scores on PTGI among subjects with moderate and high levels of exposure. There was revealed a significant association between PTG and the variant rs1306780 on the FKBP5 gene, with a higher likelihood of experiencing PTG in subjects carrying the T allele. This association seemed to be exclusively driven by the genetic effect, but not survived after multiple testing correction.
Miller, [50]	47 first-year paramedicine students (F = 28, M = 18, intersex 1; mean age = 23.43 years)	PCL-5; BRS; PTGI-X	Methylation analysis of stress genes NR3C1 and FKBP5 was performed on salivary sample of each student collected via Oragene kits (DNA Genotek)	Results reported a significant positive association between PTSD symptom severity and a total of 3 CpG sites (2 in FKBP5 and 1 in NR3C1); moreover, the correlation with CpG in the FKBP5 gene (cg07485685) was maintained after multiple testing correction. A higher severity of PTSD symptoms was significantly associated with the methylation of promotor-associated region cg03906910 of NR3C1. Lower PTSD symptoms were associated with low to moderate methylation of 2 FKBP5 5′ untranslated regions (UTRs). Lower PTG levels were significantly associated with hypermethylation of a non-promotor NR3C1 region and with hypomethylation of a promotor-associated NR3C1 region. Noticeably, NR3C1 and FKBP5 methylation appeared to be associated only with lower PTG levels and not with higher PTG levels. Lower resilience levels were significantly associated with methylation of three NR3C1 sites, while higher resilience levels were significantly associated with methylation of other two NR3C1 sites. The authors also reported a significant but opposite association between CpG site cg07485685 in gene FKBP5 and both resilience and severity of PTSD symptoms: DNA methylation at this CpG site correlated with greater resilience and with lower severity of PTSD.

PTGI: Post-Traumatic Growth Inventory; IESR: Impact of Event Scale-Revised; PCL-5: Posttraumatic Stress Disorder Checklist for DSM-5; BRS: Brief Resilience Scale; PTGI-X: Posttraumatic Growth Inventory X.