The interaction of combined effects of the BDNF and PRKCG genes and negative life events in major depressive disorder

• Major depressive disorder (MDD) is a mental disorder that results from complex interplay between genes and environmental factors.
• The BDNF and PRKCG are logical candidate genes in MDD.
• Negative life events have been suggested to exert a crucial impact on MDD.
• Gene-environment interactions were analyzed by generalized multifactor dimensionality reduction (GMDR).
• It is first reported that the BDNF- PRKCG interaction may modify the relationship between negative life events and MDD in the Chinese population.

Major depressive disorder (MDD) is a mental disorder that results from complex interplay between multiple and partially overlapping sets of susceptibility genes and environmental factors. The brain derived neurotrophic factor (BDNF) and Protein kinase C gamma type (PRKCG) are logical candidate genes in MDD. Among diverse environmental factors, negative life events have been suggested to exert a crucial impact on brain development. In the present study, we hypothesized that interactions between genetic variants in BDNF and PRKCG and negative life events may play an important role in the development of MDD. We recruited a total of 406 patients with MDD and 391 age- and gender-matched control subjects. Gene–environment interactions were analyzed using generalized multifactor dimensionality reduction (GMDR). Under a dominant model, we observed a significant three-way interaction among BDNF rs6265, PRKCG rs3745406, and negative life events. The gene–environment combination of PRKCG rs3745406 C allele, BDNF rs6265 G allele and high level of negative life events (C-G-HN) was significantly associated with MDD (OR, 5.97; 95% CI, 2.71–13.15). To our knowledge, this is the first report of evidence that the BDNF–PRKCG interaction may modify the relationship between negative life events and MDD in the Chinese population.