Causal relationship between schizophrenia and sex hormone binding globulin: A Mendelian randomization study

Schizophr Res. 2023 Sep 19:S0920-9964(23)00341-9. doi: 10.1016/j.schres.2023.09.030. Online ahead of print.

Abstract

Objective: The underlying etiology of schizophrenia is still not fully understood, and recent studies have pointed to a potential link between hormonal factors and the risk of developing this condition. Sex Hormone-Binding Globulin (SHBG) is a protein that regulates the bioavailability of sex hormones. However, the causal relationship between SHBG levels and schizophrenia remains unclear, this study aimed to investigate the causal relationship based on two-sample Mendelian randomization (MR) analysis.

Methods: This study was based on the summary data of genome-wide association studies (GWAS) of schizophrenia and SHBG in European populations. Two-sample MR was applied, and genetic factors were used as instrumental variables, and the causal relationship between schizophrenia and SHBG was assessed.

Results: We selected 79 single nucleotide polymorphisms with genome-wide significance from the schizophrenia GWAS as instrumental variables. The inverse variance weighting (IVW) method results showed that there is a causal relationship and a positive correlation between schizophrenia and female SHBG, with an odds ratio (OR) of 1.024 (95%CI: 1.007-1.042, P = 0.005), and this result was further confirmed by the Weighted median odds ratio (OR) of 1.032 (95%CI: 1.016-1.048, P = 5.58E-05) and the Weighted mode of 1.035 (95%CI: 1.004-1.067, P = 0.028). Schizophrenia and male SHBG also have a causal relationship and a positive correlation, with an odds ratio (OR) of 1.027 (95%CI: 1.007-1.047, P = 0.008).

Conclusion: This study found a positive correlation between schizophrenia and SHBG in both men and women through MR analysis, indicating that the level of SHBG may be elevated in patients with schizophrenia, regardless of gender.

Keywords: Causal relationship; Genome-wide association study; Mendelian randomization; Schizophrenia; Sex hormone binding globulin.