ABO blood groups comparing obsessive-compulsive disorder and depression

347735 Introduction: The history of studies on blood groups dates back to early 20th century. Studies have demonstrated that certain blood groups dictate tendencies toward physical or psychiatric illnesses. The present study aimed to find out the frequency of ABO and Rh blood groups in obsessive-compulsive disorder. Methods: In this survey, descriptive study with convenient samples, male/female patients who attended our psychiatry clinics with OCD (n=200) and depression (n=201) diagnosis, were enrolled according to DSM IV-TR criteria. Group one included two hundred patients with OCD (41 male and 159 female; mean age: 32.86 years) and second group consisting of two hundred and one patients were used for ABO/Rhesus (Rh) blood group antigen typing. Results: The ABO blood group phenotype distribution in OCD and depression subjects were respectively as follow: 31% (29.9%) for group A, 21% (22.9%) for group B, 40% (36.8%1) for group O and 8% (10.5%) for group AB. Rh positivity was found in 87% (85.6%1) of patients. Also, According to the Iranian Red Cross (2004), blood groups in OCD and depressive group were not significantly different from the distribution in the total Iranian population (chi-square=1.87, DF=6, p=0.93). Conclusion: According to our results, there were no differences in ABO-Rh blood groups distribution among OCD and depressive patients and normal population. Declaration of Interest: None.