Leukocyte mitochondrial DNA copy number in blood is not associated with major depressive disorder in young adults

Ying He; Jinsong Tang; Zongchang Li; Hong Li; Yanhui Liao; Yanqing Tang; Liwen Tan; Jindong Chen; Kun Xia; Xiaogang Chen

doi:10.1371/journal.pone.0096869

Leukocyte mitochondrial DNA copy number in blood is not associated with major depressive disorder in young adults

PLoS One. 2014 May 8;9(5):e96869. doi: 10.1371/journal.pone.0096869. eCollection 2014.

Authors

Ying He¹, Jinsong Tang¹, Zongchang Li², Hong Li¹, Yanhui Liao¹, Yanqing Tang³, Liwen Tan¹, Jindong Chen¹, Kun Xia⁴, Xiaogang Chen⁵

Affiliations

¹ Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China.
² Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China.
³ Department of Psychiatry, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China.
⁴ The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China.
⁵ Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China; Key Laboratory of Psychiatry and Mental Health of Hunan Province, Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China.

Abstract

Background: Major depressive disorder (MDD) is the leading cause of disability worldwide, and has significant genetic predisposition. Mitochondria may have a role in MDD and so mitochondrial DNA (mtDNA) has been suggested as a possible biomarker for this disease. We aimed to test whether the mtDNA copy number of peripheral blood leukocytes is related to MDD in young adults.

Methods: A case-control study was conducted with 210 MDD patients and 217 healthy controls (HC). The mtDNA copy number was measured by quantitative polymerase chain reaction (qPCR) method. Depression severity was assessed by the Hamilton-17 Depression Rating Scale (HDRS-17).

Results: We found no significant differences in mtDNA copy number between MDD patients and HC, though the power analysis showed that our sample size has enough power to detect the difference. There were also no significant correlations between mtDNA copy number and the clinical characteristics (such as age, age of onset, episodes, Hamilton Depression Rating Scale (HDRS) score and Global Assessment of Function Scale (GAF) score) in MDD patients.

Conclusion: Our study suggests that leukocyte mtDNA copy number is unlikely to contribute to MDD, but it doesn't mean that we can exclude the possibility of involvement of mitochondria in the disease. Further studies are required to elucidate whether mtDNA can be a biomarker of MDD.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Adult
Case-Control Studies
DNA, Mitochondrial / blood*
DNA, Mitochondrial / genetics*
Depressive Disorder, Major / blood*
Depressive Disorder, Major / genetics*
Female
Gene Dosage*
Humans
Leukocytes / metabolism*
Male
Young Adult

Substances

DNA, Mitochondrial

Grants and funding

The study was supported by the National Natural Science Foundation of China (Grant Nos. 30900486 and 81371480 to J.T., 81271484 to X.C., 81100996 to Y.L., 81071099 and 81271499 to Y.T.), and the National Key Basic Research and Development Program (973) (Grant No. 2012CB517904 to X.C.). However, the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.