This is hypothesized to cause an excess of synaptic pruning in the brain during the postnatal period ( 10).ĭifferent approaches have been used to study common and rare genetic causes of schizophrenia and have contributed to advancement in the understanding of the biology of the disorder. The strongest GWAS finding specifically for schizophrenia was the association with genetic markers across the Major Histocompatibility Complex (MHC) locus on chromosome 6 and the C4 gene. An etiological overlap between major psychiatric disorders have been found with common genetic variations in neuronal, immune and histone pathways. CNVs tend to be expressed in the developing brain suggesting a common neurodevelopmental origin for many psychiatric disorders indicating that primary prevention would need to start in childhood ( 8, 9). It is important to explain clearly that CNVs and SNVs may be inherited or they may occur de novo and that CNVs predispose to a variety of psychiatric disorders with limited diagnostic specificity. The aim is to identify the genetic influences on mental disorders and rare single-nucleotide variants (SNVs) have been associated with schizophrenia and other psychiatric disorders ( 7). It includes investigation of polygenic mechanisms and examination of copy number variants (CNVs) and potential clinical applications for polygenic risk scores that calculate the joint contribution of common variants. There has been a lot of progress in psychiatric genetics due to genome-wide association studies (GWAS) with the focus on identifying the underlying biological mechanisms contributing to disease. Some of the important findings to take into consideration will be summarized here, without going into specific gene, receptor or molecular details. Specific details about the exact gene, receptor or neurotransmitter involved are not required during the process of PGC, but the information should be detailed enough for a patient or family to make an informed decision about genetic testing. Discussion Genetic influences in the development of schizophrenia Based on this presentation, the aim of this perspective article is to summarize some of the important findings regarding the genetics of schizophrenia and to provide a brief guide for the general psychiatrist on implementation of PGC in clinical practice. To better equip psychiatrists in training for future encounters where families or patients ask questions related to the genetics of schizophrenia, a postgraduate presentation was prepared as part of the academic program at the University of Pretoria. Psychiatrists regularly have to answer questions about heritability, genetic risks and the role of genetic testing in diagnosis or treatment selection ( 6). Professional education is needed to better prepare psychiatrists to provide PGC in a manner that will assist patients and families to better understand the genetics of schizophrenia ( 5). Due to the complexity of psychiatric disorders PGC is among the most challenging topics encountered in clinical practice. It is expected that more people will seek PGC as technological and scientific advances enable more precise identification of individual genetic risks. Psychiatric genetic counseling (PGC) is a minor sub-specialty of genetic counseling that is not routinely provided for psychiatric conditions and there is a lack of consensus about the best way to deliver it to patients ( 4). The challenge psychiatrists face is the translation of the genetic findings into clinical practice to improve the lives of patients and families. There has been steady progress in the field of psychiatric genetics, generating new and fascinating insight into the genetic and phenotypic complexity of mental illness ( 3).Īdvances in psychiatric genetics has unraveled the genetic architecture of mental illness. This combination of genes do not fully control the risk of developing a mental illness and is dependent on the interaction with non-genetic factors ( 2). Vulnerability to a mental illness is a genetically complex trait that emerges from the interaction of multiple genes. The identification of genes that contribute to the risk of developing a mental disorder and influence the course of the illness is the goal of molecular genetic studies in the field. It was expected that gene discovery will transform clinical psychiatric practice, but the genetics of mental illness have been found to be enormously complex ( 2). It is well-established that the risk of schizophrenia and many other mental illnesses runs in families with adoption, twin and family studies pointing to a heredity transmission of risk. Genetic and environmental factors contribute to the susceptibility of an individual to develop schizophrenia ( 1). Major psychiatric disorders, including schizophrenia are complex, polygenic disorders.
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