Sex differences in brain gene expression among suicide completers.

BACKGROUND

Suicide rates vary substantially by sex. Suicides committed by males significantly outnumber female suicides. Disparities in community and social factors provide a partial explanation for this phenomenon. Thus, the evaluation of sex differences at a biological level might contribute to the elucidation of the factors involved in this imbalance. The aim of the present study was to evaluate sex-specific gene expression patterns in the suicidal brain.

METHODS

postmortem samples from the dorsolateral prefrontal cortex (DLPFC) of 75 Latino individuals were analyzed. We considered the following groups: i) male suicides (n = 38), ii) female suicides (n = 10), iii) male controls (n = 20), and iv) female controls (n = 7). Gene expression profiles were evaluated by microarrays. Differentially expressed genes among the groups were identified with a linear model. Similarities and differences in the gene sets between the sexes were identified.

RESULTS

Differentially expressed genes were identified between suicides and controls of each sex: 1,729 genes in females and 1,997 genes in males. Female-exclusive suicide genes were related to cell proliferation and immune response. Meanwhile, male-exclusive suicide genes were associated to DNA binding and ribonucleic protein complex. Sex-independent suicide genes showed enrichment in mitochondrial and vesicular functions.

LIMITATIONS

Relatively small sample size. Our diagnosis approach was limited to information found on coroner's records. The analysis was limited to a single brain area (DLPFC) and we used microarrays.

CONCLUSION

Previously unexplored sex differences in the brain gene expression of suicide completers were identified, providing valuable foundation for the evaluation of sex-specific factors in suicide.