Genetic explanations

• Genetic explanations suggest that OCD is inherited and that individuals receive specific genes from their parents, influencing the onset of OCD
• Genetic explanations of OCD focus on identifying specific candidate ones that are implicated in OCD
• It is believed that OCD is polygenic. Taylor ( 2003 ) suggests that as many as 230 genes may be involved in the condition.
• Two genes involved in OCD:

  COMT

  SERT
• The COMT gene in OCD - this regulates the neurotransmitter dopamine. A variation of the COMT gene increases levels of dopamine, and this variation is more common in patients with OCD
• The SERT gene in OCD - is linked to the transportation of serotonin. Transportation issues cause lower levels of serotonin to be active within the brain, and are associated with OCD. Ozaki found that in two unrelated families that both had mutations of the SERT gene, six out of seven had OCD
• AO3. There is research support from family studies. Lewis examined patients with OCD and found that 37 % of patients with OCD had parents with the disorder, and 21 % had siblings with the disorder. Nestadt claims that individuals with a first degree relative with OCD are up to five time snore likely to develop the disorder than members of the general population.
• AO3. Twin studies have provided strong evidence for a genetic basis of CD. Billett conducted meta analysis of 14 twin studies investigating the genetic inheritance rate of OCD. It was concluded that monozygotic twins had double the risk of developing OCD compared to dizygotic twins if one of the pair had the disorder. However, it could be argued that it could be down to environment too, as twins have very similar environments growing up.