FKBP5 (stress gene)

FKBP5 (FK506 Binding Protein 5) encodes a protein that regulates the sensitivity of the glucocorticoid receptor to cortisol—the main stress hormone. Variations in its expression and methylation are associated with vulnerability to post-traumatic stress disorder (PTSD), depression, and trauma disorders.

Its importance for the field of transgenerational trauma is direct: Rachel Yehuda and collaborators (2016) published in Biological Psychiatry that the children of Holocaust survivors show specific alterations in FKBP5 methylation in a key functional region (intron 7), a pattern also observed—but differentiated—in the survivors themselves. The study's conclusion: the extreme trauma suffered by the parents left verifiable epigenetic marks on children who did not experience it directly.

Beyond the Holocaust, alterations in FKBP5 have been documented in cohorts of war veterans, survivors of child abuse, and descendants of genocide victims in Cambodia and Rwanda. The pattern is robust: extreme stress → epigenetic modifications in FKBP5 → altered stress response in the next generation.

Citing FKBP5 in the systemic context allows the conversation to be anchored in concrete molecular evidence: it is not a metaphor to speak of “inheriting the clan's stress”; there is a specific gene and specific modifications that confirm it.