Genetics, family and environment The relationship between genetics and<unk>  disorders is an ongoing area of research. It is broadly understood that there exists an hereditary basis for<unk> , but the exact nature of this hereditary basis is not fully understood. While investigators have identified several genetic loci that are regions of interest for further study, there is no singular gene or set of genes that have been identified as causing<unk> . Nevertheless, genetic factors may play a role in determining whether an individual is at greater risk for developing<unk> , structural changes in the brain related to<unk> , or whether an individual is more or less likely to respond to a particular treatment modality. Genetic factors that may play a role in development of<unk>  are usually discussed in view of environmental factors (e.g., life experience or ongoing stress) that might also play a role in development of<unk> . The traditional methods of investigating the possible hereditary basis of<unk>  include using family studies and twin studies (there are no known adoption studies of individuals who suffer<unk>  disorders, including<unk> . Meta-analysis of family and twin studies suggests that there is strong evidence of a hereditary basis for<unk>  in that<unk>  is more likely to occur in first-degree relatives of individuals who have<unk>  than in non-related individuals in the same population. Twin studies also suggest that there may be a genetic linkage between<unk>  and major depressive disorder (MDD), which may explain the common occurrence of MDD in individuals who suffer<unk>  (e.g., comorbidity of MDD in individuals with<unk>  has been estimated at approximately 60%). When<unk>  is considered among all<unk>  disorders (e.g., panic disorder, social<unk>  disorder), genetic studies suggest that hereditary contribution to the development of<unk>  disorders amounts to only approximately 30-40%, which suggests that environmental factors are likely more important to determining whether an individual may develop<unk> . In regard to environmental influences in the development of<unk> , it has been suggested that parenting behaviour may be an important influence since parents potentially model<unk> -related behaviours. It has also been suggested that individuals who suffer<unk>  have experienced a greater number of minor stress-related events in life and that the number of stress-related events may be important in development of<unk>  (irrespective of other individual characteristics). Studies of possible genetic contributions to the development of<unk>  have examined relationships between genes implicated in brain structures involved in identifying potential threats (e.g., in the amygdala) and also implicated in neurotransmitters and neurotransmitter receptors known to be involved in<unk>  disorders. More specifically, genes studied for their relationship to development of<unk>  or demonstrated to have had a relationship to treatment response include: * PACAP (A54G polymorphism): remission after 6 month treatment with Venlafaxine suggested to have a significant relationship with the A54G polymorphism (Cooper et al. (2013)) * HTR2A gene (rs7997012 SNP G allele): HTR2A allele suggested to be implicated in a significant decrease in<unk>  symptoms associated with response to 6 months of Venlafaxine treatment (Lohoff et al. (2013)) * SLC6A4 promoter region (5-HTTLPR): Serotonin transporter gene suggested to be implicated in significant reduction in<unk>  symptoms in response to 6 months of Venlafaxine treatment (Lohoff et al. (2013))
Generalized anxiety disorder
Hypochondriasis
Separation anxiety disorder
Social anxiety disorder
Blood phobia
Medication phobia
Anxiety disorder
Somatization disorder