title: A systematic review of genetic variants associated with metabolic syndrome in patients with schizophrenia.
abstract: Metabolic syndrome (MetS) is a cluster of factors that increases the risk of cardiovascular disease (CVD), one of the leading causes of mortality in patients with schizophrenia. Incidence rates of MetS are significantly higher in patients with schizophrenia compared to the general population. Several factors contribute to this high comorbidity. This systematic review focuses on genetic factors and interrogates data from association studies of genes implicated in the development of MetS in patients with schizophrenia. We aimed to identify variants that potentially contribute to the high comorbidity between these disorders. PubMed, Web of Science and Scopus databases were accessed and a systematic review of published studies was conducted. Several genes showed strong evidence for an association with MetS in patients with schizophrenia, including the fat mass and obesity associated gene (FTO), leptin and leptin receptor genes (LEP, LEPR), methylenetetrahydrofolate reductase (MTHFR) gene and the serotonin receptor 2C gene (HTR2C). Genetic association studies in complex disorders are convoluted by the multifactorial nature of these disorders, further complicating investigations of comorbidity. Recommendations for future studies include assessment of larger samples, inclusion of healthy controls, longitudinal rather than cross-sectional study designs, detailed capturing of data on confounding variables for both disorders and verification of significant findings in other populations. In future, big genomic datasets may allow for the calculation of polygenic risk scores in risk prediction of MetS in patients with schizophrenia. This could ultimately facilitate early, precise, and patient-specific pharmacological and non-pharmacological interventions to minimise CVD associated morbidity and mortality.
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa; SA MRC Centre for TB Research, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa. Electronic address: smalan@sun.ac.za.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Malan-Müller
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa.
authors.forename: Sanja
authors.initials: S
authors.lastname: Kilian
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa.
authors.forename: Leigh L
authors.initials: LL
authors.lastname: van den Heuvel
authors.affiliation: SA MRC Centre for TB Research, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
authors.forename: Soraya
authors.initials: S
authors.lastname: Bardien
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa.
authors.forename: Laila
authors.initials: L
authors.lastname: Asmal
authors.affiliation: Department of Genetics, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: Louise
authors.initials: L
authors.lastname: Warnich
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa.
authors.forename: Robin A
authors.initials: RA
authors.lastname: Emsley
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa; SA MRC Centre for TB Research, DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
authors.forename: Sîan M J
authors.initials: SM
authors.lastname: Hemmings
authors.affiliation: Stellenbosch University, Department of Psychiatry, Cape Town, South Africa.
authors.forename: Soraya
authors.initials: S
authors.lastname: Seedat
mesh_terms: D014644:Genetic Variation; D006801:Humans; D024821:Metabolic Syndrome / Q000150:complications* / Q000235:genetics*; D012559:Schizophrenia / Q000150:complications* / Q000235:genetics*
keywords: Comorbidity; Gene variants; Genetic association; Metabolic syndrome; Pleiotropy; Schizophrenia