How are differences in bipolar affective disorder (manic-depressive illness) phenotypes explained?

Updated: May 06, 2018
  • Author: Stephen Soreff, MD; Chief Editor: Glen L Xiong, MD  more...
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Answer

Specific expression of common genetic variants at different times during development, or in different regions of the brain, and in concert with other genetic variants could help to explain differences in disease phenotypes. Genetic markers in 4 regions were associated with all 5 disorders, including variants in the CACNA1C gene, another gene for an L-type voltage-gated calcium channel subunit, CACNB2, and markers on chromosomes 3p21 and 10q24. [23] Although specific variants from CACNA1C showed the strongest association when only samples from individuals with bipolar disorder, major depression and schizophrenia were evaluated, the majority of regions seemed to be associated with all 5 disorders, suggesting that common risk alleles contribute to each phenotype, an effect described as pleiotropy. As noted by the authors, although CACNB2 was not identified in previous GWASs of a combined bipolar and schizophrenia sample, it was one of the main signals detected in an independentGWASs of Han Chinese individuals with bipolar disorder. [23]


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