Deletion of leukocyte mitochondrial DNA in bipolar disorder

Leukocyte mitochondrial DNA (mtDNA) was examined in 35 patients with bipolar disorder by the nested PCR method to explore whether or not the 4977 base-pair deletion (common deletion) is found. The PCR product corresponding to the common deletion was found in 2 of 35 (5.7%) patients and none of 29 normal controls. It was confirmed by the primer shift PCR method that this PCR product was amplified from deleted mtDNA. These results suggest that more than a small percentage of patients with bipolar disorder might have deleted mtDNA and that this aberrant mtDNA might relate to pathophysiology of a subtype of bipolar disorder.