genes

• concordance rates (%)


  degree of which two genetically related individuals share the same gene traits
• first degree relatives 


  50% concordance rate
• second degree relatives 


  25% concordance rate
• identical twins (MZ)

  100% concordance rate
• non identical twins (DZ)

  50% concordance rate
• MZ


  monozygotic

  identical twins
• DZ


  dizygotic

  non identical twins
• miguel et al 1997

  MZ concordance rates for OCD are higher than in DZ twins
• Mcguffin et al 


  MZ concordance rates for depression are higher than DZ twins