Mitochondria are semi-self-service organelles in eukaryotes. Their main function is to synthesize adenosine triphosphate (ATP), provide energy to cells through this pathway, and participate in a variety of activities within cells. These functions rely on the unique genetic material inside the mitochondria, known as mitochondrial DNA (mtDNA). Mitochondrial DNA abundance is the amount of mitochondrial DNA in a cell and is measured by the mitochondrial DNA copy number (mtDNA-CN). In recent years, as the scientific research community continues to deepen research on mitochondrial DNA abundance, and considering that blood mtDNA is relatively easier to obtain, researchers have begun to explore the potential relationship between blood mtDNA abundance and human health conditions and various diseases. Blood mtDNA abundance is increasingly considered as a possible biomarker for a variety of diseases. Research evidence has shown that blood mitochondrial DNA abundance is significantly correlated with diseases of human nervous system, kidney system and cardiovascular system, and can be used as a new biomarker for diagnosis and treatment. This review focuses on recent advances in the study of the association between blood mitochondrial DNA abundance and various human diseases.

Objectives:To investigate the clinical and genetic features of young Chinese patients with myeloproliferative neoplasms (MPN) .Methods:In this cross-sectional study, anonymous questionnaires were distributed to patients with MPN patients nationwide. The respondents were divided into 3 groups based on their age at diagnosis: young (≤40 years) , middle-aged (41-60 years) , and elderly (>60 years) . We compared the clinical and genetic characteristics of three groups of MPN patients.Results:1727 assessable questionnaires were collected. There were 453 (26.2%) young respondents with MPNs, including 274 with essential thrombocythemia (ET) , 80 with polycythemia vera (PV) , and 99 with myelofibrosis. Among the young group, 178 (39.3%) were male, and the median age was 31 (18-40) years. In comparison to middle-aged and elderly respondents, young respondents with MPN were more likely to present with a higher proportion of unmarried status (all P<0.001) , a higher education level (all P<0.001) , less comorbidity (ies) , fewer medications (all P<0.001) , and low-risk stratification (all P<0.001) . Younger respondents experienced headache (ET, P<0.001; PV, P=0.007; MF, P=0.001) at diagnosis, had splenomegaly at diagnosis (PV, P<0.001) , and survey (ET, P=0.052; PV, P=0.063) . Younger respondents had fewer thrombotic events at diagnosis (ET, P<0.001; PV, P=0.011) and during the survey (ET, P<0.001; PV, P=0.003) . JAK2 mutations were found in fewer young people (ET, P<0.001; PV, P<0.001; MF, P=0.013) ; however, CALR mutations were found in more young people (ET, P<0.001; MF, P=0.015) . Furthermore, mutations in non-driver genes (ET, P=0.042; PV, P=0.043; MF, P=0.004) and high-molecular risk mutations (ET, P=0.024; PV, P=0.023; MF, P=0.001) were found in fewer young respondents. Conclusion:Compared with middle-aged and elderly patients, young patients with MPN had unique clinical and genetic characteristics.

Objectives:To explore health-related quality of life (HRQoL) and identify its associated variables in Chinese patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) .Methods:In this cross-sectional study, anonymous questionnaires were distributed to adult patients with MPNs to assess symptom burden measured by MPN-10 and HRQoL measured by Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) .Results:The data from 1405 respondents with MPNs, including 645 (45.9%) with essential thrombocythemia (ET) , 297 (21.1%) with polycythemia vera (PV) , and 463 (33.0%) with myelofibrosis (MF) , were analyzed. 646 (46.0%) respondents were male. The median age was 56 (range, 18-99) years. The mean MPN-10 scores were 13.0±12.7, 15.0±14.7, and 21.0±16.6 ( P<0.001) , and the physical component summary (PCS) and mental component summary (MCS) scores were 48.0±8.5, 47.0±9.0, and 42.0±10.0 ( P<0.001) and 51.0±11.0, 50.0±10.8, and 49.0±11.1 ( P=0.002) for respondents with ET, PV, and MF, respectively. Respondents with MF reported the lowest score of physical functioning, role functioning, emotional functioning, cognitive functioning, social function, and global health status (all P<0.01) and the highest score of fatigue, pain, dyspnea, appetite loss, diarrhea, and financial problems (all P<0.05) in EORTC QLQ-C30. Multivariate analyses revealed that higher MPN-10 scores were significantly associated with lower PCS (-0.220 to -0.277, P<0.001) and MCS (-0.244 to -0.329, P<0.001) scores; increasing age (-1.923 to -4.869; all P<0.05) , lower PCS score. Additionally, comorbidity (ies) , symptom at diagnosis, splenomegaly, anemia, unknown driver gene, and higher annual out-of-pocket cost were significantly associated with lower PCS and/or MCS scores. However, age ≥ 60 years, urban household registration, concomitant medication, and receiving ruxolitinib therapy in respondents with MF were associated with higher MCS scores. Weak correlations were found between MPN-10 score (except the subscale of appetite loss and constipation) and EORTC QLQ-C30 score in majority of subscales in respondents with ET (| r| = 0.193-0.457, all P<0.001) , PV (| r| = 0.192-0.529, all P<0.01) , and MF (| r| = 0.180-0.488, all P<0.001) , respectively. Conclusions:HRQoL in patients with MPN was significantly reduced, especially in patients with MF. Sociodemographic and clinical variables were significantly associated with the HRQoL in patients with MPNs.