Although the exact cause of bipolar disorder is unknown, the NIH states that “it occurs more often in relatives of people with bipolar disorder”. This statement alone means that bipolar disorder has a genetic cause and this may explain why its physical causes may not be readily known. Studies have also proven the same, like twin, family and adoption studies that support “the existence of genes that predispose [one] to bipolar disorder”. The percentage of heritability of bipolar disorder, based on scientific studies on the matter, is around 60%, and this was proven by several genome-wide association studies, or GWAS, which try to resolve a disease by studying its genetic causes (Gershon et al.). Nevertheless, some other possible non-genetic causes of bipolar disorder include major life changes especially those that may bring about so much stress, periods of sleeplessness, antidepressant or steroid medications or other similar types, and use of recreational drugs. Overall, the problem with bipolar disorder and the need to investigate its genetic causes is that bipolar disorder is the reason for the “loss of more disability-adjusted life-years than all forms of cancer or major neurologic conditions such as epilepsy or Alzheimer’s disease”. In fact, this claim is usually associated with the fact that bipolar disorder has an “early onset and chronicity across a lifespan”. In short, bipolar disorder is more dangerous and harmful to the mental and physical health of an individual more than anyone could ever imagine.
Brief Survey of Related Literature
Several recent research studies have pointed out the theory that there is indeed a genetic basis for the occurrence of bipolar disorder.
Copy number variants, or CNVs, which naturally occur in the human genome, may play a role in the occurrence of bipolar disorder in an individual and may determine one’s susceptibility to the disease (Grozeva et al. 320). In fact, CNVs have been associated with and implicated in the existence of several neuropsychiatric phenotypes as well as schizophrenia, mental retardation, epilepsy and autism. These CNVs are large, rare deletions that occur in the human genome and may predispose one to the disease. So far, the study of Grozeva et al. in 2010 has found out that the genetic cause of bipolar disorder is “2 genes involved in ion channel function [which are namely] ANK3 and CACNA1C” (Grozeva et al. 322). Aside from these two genes, other genes that may make an individual susceptible to bipolar disorder include PALB2, MYO5B and DGKH. So far, based on this study, there was a natural increase in the number of singleton CNVs in cases of bipolar disorder compared to those who were healthy (Grozeva et al. 325).
According to the consortium study of recurrent depression by the Genetic Association Information Network, or GAIN, there is “nominally significant” evidence that the CACNA1C gene is mainly involved in the hereditary nature of bipolar disorder. However, the CACNA1C gene is not specific to bipolar disorder as this particular gene increases the individual’s risk for schizophrenia and recurrent major depression as well (Green et al. 1018).
SNPs or single nucleotide polymorphisms are also another possible factor that might explain the genetic basis of bipolar