Since the Human Genome Project, researchers have been searching for genetic links to various medical conditions. Many diseases have been found to be linked to genes inherited from parents, which can increase susceptibility to a variety of illnesses.
Recent research has discovered genetic links between various mental illnesses and their predisposition, which could be inherited by children with a family history of psychiatric disorders.
Genetic Predisposition to Mental Illness
In 1990, a paper was published by St Clair and colleagues that studied a large family from Edinburgh and discovered that differences at the q21-22 region on chromosome 11 presented genetic susceptibility to mental illness.
This sparked other researchers to further understand if mental illnesses can be passed to the next generation through parents’ genes.
The present research has been done to determine specific genes that are associated with mental illness manifestation in an individual.
Studies have shown that schizophrenia, depression, bipolar disorder have genetic links to its predisposition.
Specifically, DISC – 1 (disrupted in schizophrenia 1) a protein whose gene is located on chromosome 1 was found to show the predisposition to schizophrenia and depression.
A mutated DISC – 1 gene in mice resulted in abnormal DISC – 1 protein formation, which was investigated to be related to a number of cellular activities in the brain, such as, protein interactions at the brain cell network and cell multiplication.
Aberrant formation of DISC – 1 protein thus leads to abnormal brain cell functioning and could predispose the individual to psychiatric disease.
Single nucleotide polymorphisms in the CACNA1C gene was also found to affect susceptibility to major depression disorder (MDD). CACNA1C gene which codes for the alpha 1C subunit of a voltage-dependent calcium channel which means it’s a protein that utilizes changes in cellular voltage for the cell to transport calcium.
Single nucleotide polymorphisms (SNP) are genetic variation in a single nucleotide in a DNA sequence (A, T, C or G) which varies between paired chromosomes. The research was done by Backes. H and colleagues discovered that patients with (Major Depression Disorder) MDD produced more than normal amounts of the CACNA1C protein.
This is especially so if the patient inherited the A allele of a specific SNP position (rs1006737). This variation later led them to observe that there were differences in the prefrontal and cerebellar regions of the brain. These two areas focus on personality development and muscle coordination respectively.
Overcoming Genetic Inheritance with Environmental Factors
Despite the research showing that one can genetically inherit mental illnesses through specific genes, these only show that there is a higher predisposition for individuals if these abnormal genes or SNPs are present.
The environment that a child is brought up in can also influence whether the psychiatric disorder can truly manifest.
This was done through gene-environment correlation studies, it discusses the association between the genotype inherited and the environment the child is brought up can influence the genetic effects of inherited mental illness.
This means that even with the genetic inheritance of genes that influence mental illnesses or family history, exposure to the environment can also play an important role in the development of psychiatric disorders.
With increasing links between genes and mental illnesses being discovered psychiatric genetic counseling has been made available especially if there is the family history of any kind of major psychiatric disorder.
A pilot study was done in 2008 where a group of subjects participated in a psychiatric genetic counseling session for parents of individuals affected with psychotic disorders. This research showed that there was a better understanding amongst the participants that inheriting psychiatric illnesses could be influenced by genes and environment.
Don’t be too worried if there is the history of the psychiatric disease in your family, genetic factors linked to behavior and mental illnesses inheritance can be subdued by environmental exposures.
- Backes H, Dietsche B, Nagels A, Konrad C, Witt SH, Rietschel M, Kircher T, and Krug A (2014) Genetic variation in CACNA1C affects neural processing in major depression, Journal of Psychiatric Research, 38- 46
- Nicholas J. Brandon, J. Kristy Millar, Carsten Korth, Hazel Sive, Karun K. Sing, and Akira Sawa (2009) Understanding the Role of DISC1 in psychiatric disease and during Normal Development, Journal of Neuroscience, 29 (41) 12768-12775; https://www.jneurosci.org/content/29/41/12768
- St Clair, D. Blackwood, W. Muir, M. Walker, D. St Clair, W. Muir, A. Carothers, G. Spowart, C. Gosden, H.J. Evans, Association within a family of a balanced autosomal translocation with major mental illness, In The Lancet, Volume 336, Issue 8706, 1990, Pages 13-16, ISSN 0140-6736, https://doi.org/10.1016/0140-6736(90)91520-K. https://www.sciencedirect.com/science/article/abs/pii/014067369091520K
- Knafo, A., & Jaffee, S. (2013). Gene-environment correlation in developmental psychopathology. Development and Psychopathology, 25(1), 1-6. doi:10.1017/S0954579412000855
- Austin, J. C., and Honer, W. G. (2008), Psychiatric genetic counseling for parents of individuals affected with psychotic disorders: a pilot study. Early Intervention in Psychiatry, 2: 80–89.
- Jaffee, S., & Price, T. (2007). Gene-environment correlations: a review of the evidence and implications for prevention of mental illness. Molecular Psychiatry, 12(5), 432–442. https://www.nature.com/articles/4001950