Genetic

• The COMT gene regulates the neurotransmitter dopamine.
• One variation of the COMT gene results in higher levels of dopamine.
• This variation is more common in patients with OCD compared to people without OCD.
• A faulty COMT gene is linked to OCD.
• Too much dopamine=OCD
• The SERT gene also known as the 5-HTT gene is linked to serotonin.
• The SERT gene affects the transportation of this neurotransmitter (hence SERotonin Treatment).
• If there is a mutation in the SERT gene, this can lead to OCD.
• This is due to decreased serotonin transportation.
• Ozaki et al(2003) studied two unrelated families who both had mutations of the SERT gene, 6/7 family members had OCD.
• Two genes have been linked to OCD including the COMT gene and SERT gene.
• The COMT gene is associated with the production of catechol-O-methyltransferase, which regulates the neurotransmitter dopamine.
• High levels of dopamine produced by the COMT gene have been implicated in OCD.
• The SERT gene (5-HTT gene) has also been implicated in cases of OCD.
• Genetic explanations suggest OCD is inherited and that individuals inherit specific genes which cause OCD.
• Genetic explanations suggest behaviour is inherited through biological mechanisms.
• Lewis (1936) observed that of his OCD patients, 37% also had OCD parents, and 21% had siblings with OCD.
• Taylor (2013) found up to 230 different genes implicated in OCD.
• OCD is believed to be polygenic (caused by more than one gene).
• The genetic explanation is closely linked to the neural explanation, in that candidate genes play a part in neurotransmitter production.
• What is one strength of the genetic explanation for OCD?

  There is supporting evidence.
• What did Lewis (1936) find in his study of patients with OCD?

  37% of patients with OCD had parents with the disorder.
• What percentage of patients with OCD had siblings with the disorder according to Lewis (1936)?

  21%
• What did Nestadt et al. (2000) propose about individuals with a first-degree relative with OCD?

  They are up to five times more likely to develop the disorder.
• How does family study research support the genetic explanation for OCD?

  It shows a higher likelihood of developing OCD among those with a family history.
• What does the research from family studies suggest about the role of environmental factors in OCD?

  It does not rule out other environmental factors playing a role.