Anxiety disorders are one of the most complex psychological disorders in existence and also one of the least understood, etiologically. It is extremely important to understand anxiety disorders from an etiologically genetic standpoint, because it often explains why those people who experience the same environment react differently- why some develop an anxiety disorder, whereas others don't. This is what is known as the GXE Interaction. For example, adults who suffered child abuse are susceptible to developing Post-Traumatic Stress Disorder, a type of anxiety disorder, as a result. However, some people will develop PTSD whereas others won't, even though they experienced the same trauma. The research of GXE often separates the etiology and probability that any one person will develop an anxiety disorder as opposed to those who won't in the same environment, which is why it is so critical that we understand its effect on anxiety.
There are two types of anxiety: state anxiety and trait anxiety; state anxiety is that anxiety which a person experiences from ordinary, ?normal', life events, such as job stress- it is temporary and tends to be mild to moderate. Trait anxiety however, is that anxiety that a person experiences constantly- it is moderate to severe and often debilitating (Belzung, Calatayud, and Clement, 2002). We will only be concerned with trait anxiety- which encompasses all of the anxiety disorders- for this essay.
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[...] Costa, et al. measured 425 men and women with either the homozygous recessive or heterozygous candidate genotype and their corresponding (personality) phenotype, using the Temperament and Character Inventory. (Their genotypes were determined using polymerase chain reaction, gel electrophoresis, and denaturation techniques.) In order to confirm the veridicality of the 5-HTT assay, sixty other subjects were randomly assigned (to participate) with 100% interlaboratory unanimity. Positive correlations were found for anxiety levels and allelic frequencies in each group; however, the results were never replicated. [...]