Which genes are likely to influence the susceptibility to major depressive disorder (clinical depression)?

Updated: Aug 06, 2020
  • Author: Jerry L Halverson, MD; Chief Editor: David Bienenfeld, MD  more...
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Although multiple genes are likely to influence the susceptibility to depression, those involved in the serotonin system are a focus of investigation, especially because many antidepressant medications work by influencing serotonin. [18] The SLC6A4 gene, which is located at 17q11.2, encodes a serotonin transporter (also known as 5-hydroxytryptamine transporter) that is responsible for actively clearing serotonin from the synaptic space.

A polymorphism in the promoter region of the SLC6A4 gene consists of a 44bp insertion or deletion involving repeat elements. These polymorphisms are referred to as either a long allele or a short allele. Caspi et al found that persons who were homozygous or heterozygous for the short allele had more depressive symptoms and suicidality in association with stressful life events than those patients who were homozygous for the long allele. [19]

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