Psychogenetics of phobia
Inheritance of phobia is thought to be autosomal dominant. Few genes have been implicated in phobia and their inheritance and effect on phenotype remain unclear. A duplication on chromosome 15, DUP25, and a polymorphism in the COMT (catechol-O-methyltransferase) gene and another in the upstream region of the serotonin transporter gene (SLC6A4) which reduces transcription, have all been identified as possible susceptibility factors. The involvement of serotonin in phobia has been known for some time and COMT has links with the sympathetic nervous system, however the effect of DUP25 in this condition, if any, is unclear.
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References
Panic disorder. Online Mendelian Inheritance in ManTM, National Library of Medicine, National Institutes of Health. http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=167870. Accessed on 21 January 2003