Relationship of mitochondrial DNA copy number with clinicopathological characteristics and its influence on the prognosis of hepatocellular carcinoma patients
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摘要:目的
探讨肝细胞癌病人线粒体DNA拷贝数与临床病理特征的关系及对预后的影响。
方法采用回顾性队列研究方法。收集2011年3—6月海军军医大学附属东方肝胆外科医院收治的71例行手术切除肝细胞癌病人的临床病理资料;男61例,女10例;中位年龄为55岁,年龄范围为26~80岁。所有病人检测肝癌组织和癌旁组织线粒体DNA拷贝数。观察指标:(1)肝细胞癌病人肝癌组织和癌旁组织线粒体DNA拷贝数及其与临床病理特征的关系。(2)随访情况。(3)肝细胞癌病人预后影响因素分析。采用门诊或电话方式进行随访,了解病人术后生存情况。随访时间截至2019年9月。正态分布的计量资料以x±s表示,组间比较采用独立样本t检验或配对样本t检验。偏态分布的计量资料以M(范围)表示。计数资料以绝对数表示,组间比较采用χ²检验或Fisher确切概率法。单因素和多因素分析均采用COX回归模型,单因素分析中P<0.10的指标纳入多因素分析。采用Kaplan‑Meier法计算生存率和绘制生存曲线,采用Log‑rank检验进行生存分析。
结果(1)肝细胞癌病人肝癌组织和癌旁组织线粒体DNA拷贝数及其与临床病理特征的关系:71例肝细胞癌病人肝癌组织线粒体DNA拷贝数为0.85±0.08,癌旁组织线粒体DNA拷贝数为1.16±0.08,两者比较,差异有统计学意义(t=2.96,P<0.05)。71例病人中,48例为线粒体DNA低拷贝数,23例为线粒体DNA高拷贝数。线粒体DNA低拷贝数和高拷贝数病人肿瘤包膜(完整、不完整)和微血管侵犯(有、无)分别为20、28例,21、27例和16、7例,4、19例,上述指标比较,差异均有统计学意义(χ²=4.84,4.74,P<0.05)。(2)随访情况:71例病人均获得随访,随访时间为2.1~85.3个月,中位随访时间为47.8个月。71例病人1、3、5年总体生存率分别为87.3%、64.7%、37.4%。48例线粒体DNA低拷贝数病人1、3、5年总体生存率分别为81.2%、50.0%、29.2%;23例线粒体DNA高拷贝数病人1、3、5年总体生存率分别为95.7%、86.5%、54.7%,两者生存情况比较,差异有统计学意义(χ²=5.86,P<0.05)。(3)肝细胞癌病人预后影响因素分析:单因素分析结果显示肿瘤数目、门静脉癌栓、微血管侵犯、巴塞罗那临床肝癌分期、线粒体DNA拷贝数是影响肝细胞癌病人预后的相关因素(风险比=2.211,2.911,3.899,3.587,0.440,95%可信区间为1.024~4.777,1.485~5.704,2.115~7.186,1.615~7.966,0.223~0.871,P<0.05)。多因素分析结果显示:微血管侵犯和线粒体DNA拷贝数是肝细胞癌病人预后的独立影响因素(风险比=2.754,0.437,95%可信区间为1.374~5.521,0.205~0.932,P<0.05)。
结论肝细胞癌病人线粒体DNA拷贝数与肿瘤包膜、微血管侵犯有关;微血管侵犯和线粒体DNA拷贝数是肝细胞癌病人预后的独立影响因素。
Abstract:ObjectiveTo investigate the relationship of mitochondrial DNA (mtDNA) copy number with clinicopathologic characteristics and its influence on the prognosis of hepatocellular carcinoma (HCC) patients.
MethodsThe retrospective case-control study was conducted. The clinicopathological data of 71 HCC patients undergoing surgical treatment in the Eastern Hepatobiliary Surgery Hospital of Naval Medical University from March to June 2011 were collected. There were 61 males and 10 females, aged from 26 to 80 years, with a median age of 55 years. The mtDNA copy number of tumor tissues and adjacent normal tissues were measured for all patients. Observation indicators: (1) the mtDNA copy number of tumor tissues and adjacent normal tissues and relationship between the mtDNA copy number and clinicopathological characteristics of HCC patients; (2) follow-up; (3) related factors for the prognosis of HCC patients. Follow-up using outpatient examination or telephone interview was conducted to detect postoperative survival of patients up to September 2019. Measurement data with normal distribution were described as Mean±SD, and comparison between groups was analyzed using independent samples t test or the matched samples t test. Measurement data with skewed distribution were described as M(range). Count data were represented as absolute numbers, and comparison between groups was analyzed using the chi-square test or Fisher exact probability. Univariate and multivariate analyses were conducted using the COX regressional model. Variables with P<0.10 in the univariate analysis were included for the multivariate analysis. Survival rates were calculated using the Kaplan-Meier method, and Log-rank test was used for survival analysis.
Results(1) The mtDNA copy number of tumor tissues and adjacent normal tissues and relationship between the mtDNA copy number and clinicopathological characteristics of HCC patients: of 71 HCC patients, the mtDNA copy number was 0.85±0.08 in tumor tissues, versus 1.16±0.08 in adjacent normal tissues, showing a significant difference between them (t=2.96, P<0.05). Of 71 HCC patients, 48 cases were mtDNA-low and 23 cases were mtDNA-high. Cases with tumor capsule as integrity or not-integrity, cases with or without microvascular (MVI) in mtDNA-low and mtDNA-high patients were 20, 28, 21, 27 and 16, 7, 4, 19, respectively, showing significant differences (χ2=4.84, 4.74, P<0.05). (2) Follow-up: 71 patients were followed up for 2.1 to 85.3 months, with a median follow-up time of 47.8 months. The 1-, 3-, 5-year overall survival rates of 71 HCC patients were 87.3%, 64.7, 37.4%, respectively. Moreover, the 1-, 3-, 5-year overall survival rates were 81.2%, 50.0%, 29.2% of the mtDNA-low patients, versus 95.7%, 86.5%, 54.7% of the mtDNA-high patients, showing a significant difference between the two groups (χ2=5.86, P<0.05). (3) Related factors for the prognosis of HCC patients. Results of univariate analysis showed that the number of tumor, portal vein tumor thrombus, MVI, Barcelona Clinic Liver Cancer stage, mtDNA copy number were related factors for the prognosis of HCC patients (hazard ratios=2.211, 2.911, 3.899, 3.587, 0.440, 95% confidence intervals as 1.024‒4.777, 1.485‒5.704, 2.115‒7.186, 1.615‒7.966, 0.223‒0.871, P<0.05). Results of multivariate analysis showed that MVI and mtDNA copy number were independent influencing factors for the prognosis of HCC patients (hazard ratios=2.754, 0.437, 95% confidence intervals as 1.374‒5.521, 0.205‒0.932, P<0.05).
ConclusionsThe mtDNA copy number of HCC patients is related with tumor capsule and MVI. The mtDNA copy number and MVI are independent influencing factors for the prognosis of HCC patients.
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Keywords:
- Liver neoplasms /
- Mitochondrial /
- Deoxyribonucleic acid /
- Pathology /
- Pro-gnosis /
- Analysis
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肝细胞癌是全世界恶性肿瘤相关死亡的第4大常见原因[1]。现有治疗措施可使部分肝细胞癌病人获得远期生存,但其容易复发和转移的特性导致总体疗效不理想[2⁃4]。肿瘤细胞通过系列分子调节机制,导致部分基因表达及功能改变,从而使肿瘤细胞表现为恶性生长特性,其中线粒体DNA改变具有重要作用。线粒体DNA改变主要表现为片段缺失、碱基突变以及拷贝数改变3种形式,拷贝数改变处于中心位置[5‑6]。研究者在肾细胞癌、乳腺癌和食管癌等多种恶性肿瘤中发现线粒体DNA拷贝数改变对肿瘤生物学活性有重要影响[7‑10]。还有研究者发现线粒体DNA拷贝数与结直肠癌、早期喉癌、胆管细胞癌的预后和肿瘤转移有关[11‑13]。目前研究尚未发现线粒体DNA拷贝数与肝细胞癌预后的相关性[14⁃15]。本研究回顾性分析2011年3—6月海军军医大学第三附属医院肝外四科收治的71例行手术切除肝细胞癌病人的临床病理资料,探讨肝细胞癌病人线粒体DNA拷贝数与临床病理特征的关系及对预后的影响。
资料与方法
一、一般资料
采用回顾性队列研究方法。收集71例行手术切除肝细胞癌病人的临床病理资料;男61例,女10例;中位年龄为55岁,年龄范围为26~80岁。本研究通过海军军医大学第三附属医院医学伦理委员会审批,批号为EHBHKY2019⁃01⁃001。病人及家属均签署知情同意书。
二、纳入标准和排除标准
纳入标准:(1)术后组织病理学检查证实为R0切除。(2)术后组织病理学诊断为肝细胞癌。(3)临床病理资料完整。
排除标准:(1)术前接受其他抗肿瘤治疗,如RFA、经肝动脉灌注化疗等。(2)合并其他部位的恶性肿瘤。(3)临床病理资料缺失。
三、线粒体DNA拷贝数检测
参照文献[15]收集肝细胞癌病人的肝癌组织与癌旁组织标本,置于液氮冷冻后于‒80 ℃保存。采用实时荧光定量PCR方法,以β‑actin为内参照对线粒体DNA还原型烟酰胺腺嘌呤二核苷酸脱氢酶亚基1(NADH dehydrogenase subunit 1,ND1)进行相对定量检测。PCR引物:正向5′‑ATACAACTACG⁃CAAAGGCCCCA‑3′;反向5′‑AATAGGAGGCCTAG⁃ GTTGAGGT‑3′。反应体系为SybrGreen qPCR Master Mix(2X,购自上海睿安生物公司)12.5 μL,引物正向、反向(10 μmol/L)各0.5 μL,双蒸水9.5 μL,总DNA 2 μL。总反应体积25 μL。PCR反应条件为95 ℃,15 min预变性,后95 ℃ 10 s,60 ℃ 60 s,共45个循环。定量PCR仪为ABI7500 FAST型荧光定量PCR仪(美国应用生物系统公司产品)。分别检测病人肝癌组织与癌旁组织线粒体DNA拷贝数。
四、观察指标和评价标准
观察指标:(1)肝细胞癌病人肝癌组织和癌旁组织线粒体DNA拷贝数及其与临床病理特征的关系包括性别、年龄、肿瘤长径、AFP、HBsAg、HBeAg、肿瘤包膜、肝硬化、肿瘤数目、门静脉癌栓、微血管侵犯、巴塞罗那临床肝癌(Barcelona clinic liver cancer,BCLC)分期。(2)随访情况:获得随访病人例数,随访时间,1、3、5年生存情况。(3)肝细胞癌病人预后影响因素分析:性别、年龄、肿瘤长径、AFP、HBsAg、HBeAg、肿瘤包膜、肝硬化、肿瘤数目、门静脉癌栓、微血管侵犯、BCLC分期、线粒体DNA拷贝数。
评价标准:肝细胞癌病理学诊断参考《原发性肝癌诊疗规范(2019版)》[16]。肝癌组织与癌旁组织线粒体DNA拷贝数比值<1定义为线粒体DNA低拷贝数,≥1为高拷贝数[14]。
五、随访
采用门诊或电话方式进行随访,了解病人术后生存情况。随访时间截至2019年9月。
六、统计学分析
应用SPSS 25.0统计软件进行分析。正态分布的计量资料以x±s表示,组间比较采用独立样本t检验或配对样本t检验。偏态分布的计量资料以M(范围)表示。计数资料以绝对数表示,组间比较采用χ²检验或Fisher确切概率法。单因素和多因素分析均采用COX回归模型,单因素分析中P<0.10的指标纳入多因素分析。采用Kaplan‑Meier法计算生存率和绘制生存曲线,采用Log‑rank检验进行生存分析。P<0.05为差异有统计学意义。
结果
一、肝细胞癌病人肝癌组织和癌旁组织线粒体DNA拷贝数及其与临床病理特征的关系
71例肝细胞癌病人肝癌组织线粒体DNA拷贝数为0.85±0.08,癌旁组织线粒体DNA拷贝数为1.16±0.08,两者比较,差异有统计学意义(t=2.96,P<0.05)。71例病人中,48例为线粒体DNA低拷贝数,23例为线粒体DNA高拷贝数。线粒体DNA低拷贝数和高拷贝数病人肿瘤包膜、微血管侵犯比较,差异均有统计学意义(P<0.05);性别、年龄、肿瘤长径、AFP、HBsAg、HBeAg、肝硬化、肿瘤数目、门静脉癌栓、BCLC分期比较,差异均无统计学意义(P>0.05)。见表1。
表 1 不同线粒体DNA拷贝数肝细胞癌病人的临床病理特征比较Table 1. Comparision of clinicopathological parameters in hepatocellular carcinoma patients with different mitochondrial DNA copy numbers分类 例数 性别(例) 年龄(x±s,岁) 肿瘤长径(例) 甲胎蛋白(例) 乙型肝炎表面抗原(例) 乙型肝炎e抗原(例) 男 女 ≤50 mm >50 mm <20 μg/L ≥20 μg/L 阴性 阳性 阴性 阳性 线粒体DNA 低拷贝数 48 41 7 53±10 15 33 17 31 8 40 35 13 线粒体DNA 高拷贝数 23 20 3 54±10 12 11 9 14 3 20 15 8 统计值 - t=0.94 χ²=2.89 χ²=0.92 - χ²=0.44 P值 >0.05a >0.05 >0.05 >0.05 >0.05a >0.05 注: 线粒体DNA低拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值<1,线粒体DNA高拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值≥1;“‒”为此项无;a采用Fisher确切概率法二、随访情况
71例病人均获得随访,随访时间为2.1~85.3个月,中位随访时间为47.8个月。71例病人1、3、5年总体生存率分别为87.3%、64.7%、37.4%。见图1。48例线粒体DNA低拷贝数病人1、3、5年总体生存率分别为81.2%、50.0%、29.2%;23例线粒体DNA高拷贝数病人1、3、5年总体生存率分别为95.7%、86.5%、54.7%,两者生存情况比较,差异有统计学意义(χ²=5.86,P<0.05)。见图2。
三、肝细胞癌病人预后影响因素分析
单因素分析结果显示:肿瘤数目、门静脉癌栓、微血管侵犯、BCLC分期、线粒体DNA拷贝数是影响肝细胞癌病人预后的相关因素(P<0.05)。性别、年龄、肿瘤长径、AFP、HBsAg、HBeAg、肿瘤包膜、肝硬化不是影响肝细胞癌病人预后的相关因素(P>0.05)。见表2。
表 2 影响71例肝细胞癌病人预后的单因素分析Table 2. Univariate analysis of survival in 71 hepatocellular carcinoma patients临床病理因素 赋值 例数 5年总体生存率(%) 风险比(95%可信区间) P值 性别 男 1 61 38.7 1.129(0.504~2.529) >0.05 女 0 10 30.0 年龄(岁) ≤60 0 54 37.0 1.184(0.600~2.339) >0.05 >60 1 17 39.2 肿瘤长径(mm) ≤50 0 27 48.1 >50 1 44 30.6 1.626(0.873~3.029) >0.05 甲胎蛋白(μg/L) <20 0 26 48.6 1.891(0.991~3.607) >0.05a ≥20 1 45 31.1 乙型肝炎表面抗原 阴性 0 11 31.8 0.905(0.404~2.030) >0.05 阳性 1 60 38.3 乙型肝炎e抗原 阴性 0 50 37.1 0.982(0.515~1.871) >0.05 阳性 1 21 38.1 肿瘤包膜 完整 0 36 46.2 不完整 1 35 28.6 0.573(0.318~1.033) >0.05a 肝硬化 无 0 38 30.2 0.756(0.418~1.366) >0.05 有 1 33 45.5 肿瘤数目 单个 0 63 40.7 2.211(1.024~4.777) <0.05 多个 1 8 12.5 门静脉癌栓 无 0 57 43.9 2.911(1.485~5.704) <0.05 有 1 14 8.6 微血管侵犯 无 0 46 52.2 3.899(2.115~7.186) <0.05 有 1 25 8.9 巴塞罗那临床肝癌分期(期) 0~A 1 25 52.0 1.443(0.717~2.904) >0.05 B 2 32 37.5 3.587(1.615~7.966) <0.05 C 3 14 8.6 线粒体DNA拷贝数 高 0 23 54.7 0.440(0.223~0.871) <0.05 低 1 48 29.2 注: 线粒体DNA低拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值<1,线粒体DNA高拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值≥1;a0.05<P<0.10多因素分析结果显示:微血管侵犯和线粒体DNA低拷贝数是肝细胞癌病人预后的独立影响因素(P<0.05)。见表3。
表 3 影响71例肝细胞癌病人预后的多因素分析Table 3. Multivariate analysis of survival in 71 hepato⁃ cellular carcinoma patients临床病理因素 b值 标准误 Wald值 风险比(91%可信区间) P值 甲胎蛋白 0.659 0.366 3.246 1.932(0.944~3.956) >0.05 肿瘤包膜 0.170 0.359 0.225 1.186(0.586~2.398) >0.05 肿瘤数目 0.479 0.423 1.279 1.614(0.704~3.700) >0.05 门静脉癌栓 0.687 0.727 0.893 1.989(0.478~8.276) >0.05 微血管侵犯 1.013 0.355 8.156 2.754(1.374~5.521) <0.05 巴塞罗那临床肝癌分期 -0.083 0.399 0.043 0.921(0.421~2.012) >0.05 线粒体DNA拷贝数 -0.827 0.386 4.589 0.437(0.205~0.932) <0.05 讨论
线粒体DNA是核外唯一具有遗传效应的物质,作为一种结构相对简单而精致的真核生物基因组,编码了2个rRNA、22个tRNA以及13个与氧化磷酸化有关的多肽,是控制线粒体功能的主要因素[17‑19]。现有研究结果显示:线粒体DNA的改变对肿瘤的发生及发展有重要影响,在多个肿瘤组织中,均可发现线粒体DNA的改变[20‑25]。在人体肝癌细胞中,也发现线粒体DNA D‑loop区的突变及拷贝数下降,以及线粒体DNA片段缺失,并认为其对肝癌的产生、增殖以及转移有重要影响[26]。正常情况下,每个人类细胞平均包含100~500个线粒体,每个线粒体含有2~10个线粒体DNA拷贝数[27]。拷贝数会随组织细胞类型而改变,并受到细胞分化、激素刺激及锻炼等各种因素影响[28‑29]。本研究结果显示:肝细胞癌病人肝癌组织线粒体DNA拷贝数显著低于癌旁组织,这与既往研究结果一致[14]。
线粒体DNA拷贝数在不同肿瘤中与多种临床病理特征相关[30]。本研究根据肝癌组织和癌旁组织的线粒体DNA拷贝数比值将病人分为两类,其结果显示:与线粒体DNA高拷贝数肝细胞癌病人比较,线粒体DNA低拷贝数病人更易出现肿瘤包膜不完整和微血管侵犯。提示肝细胞癌病人线粒体DNA拷贝数降低可能与肿瘤的恶性病理学特征相关。本研究结果显示:线粒体DNA高拷贝数病人的生存情况显著优于线粒体DNA低拷贝数病人,与既往研究结果不一致[14]。推测可能与本研究纳入病例数较少有关。此外,本研究结果显示:微血管侵犯和线粒体DNA拷贝数是肝细胞癌病人预后的独立影响因素,这与既往研究结果一致[31‑33]。
综上,肝细胞癌病人线粒体DNA拷贝数与肿瘤包膜、微血管侵犯有关;微血管侵犯和线粒体DNA拷贝数是肝细胞癌病人预后的独立影响因素。
所有作者均声明不存在利益冲突陈芳芳, 彭祖祥, 皮儒先, 等. 肝细胞癌病人线粒体DNA拷贝数与临床病理特征的关系及对预后的影响[J]. 中华消化外科杂志, 2021, 20(12): 1306-1312. DOI: 10.3760/cma.j.cn115610-20211101-00535.http://journal.yiigle.com/LinkIn.do?linkin_type=cma&DOI=10.3760/cma.j.cn115610-20211101-00535
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表 1 不同线粒体DNA拷贝数肝细胞癌病人的临床病理特征比较
Table 1 Comparision of clinicopathological parameters in hepatocellular carcinoma patients with different mitochondrial DNA copy numbers
分类 例数 性别(例) 年龄(x±s,岁) 肿瘤长径(例) 甲胎蛋白(例) 乙型肝炎表面抗原(例) 乙型肝炎e抗原(例) 男 女 ≤50 mm >50 mm <20 μg/L ≥20 μg/L 阴性 阳性 阴性 阳性 线粒体DNA 低拷贝数 48 41 7 53±10 15 33 17 31 8 40 35 13 线粒体DNA 高拷贝数 23 20 3 54±10 12 11 9 14 3 20 15 8 统计值 - t=0.94 χ²=2.89 χ²=0.92 - χ²=0.44 P值 >0.05a >0.05 >0.05 >0.05 >0.05a >0.05 注: 线粒体DNA低拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值<1,线粒体DNA高拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值≥1;“‒”为此项无;a采用Fisher确切概率法表 2 影响71例肝细胞癌病人预后的单因素分析
Table 2 Univariate analysis of survival in 71 hepatocellular carcinoma patients
临床病理因素 赋值 例数 5年总体生存率(%) 风险比(95%可信区间) P值 性别 男 1 61 38.7 1.129(0.504~2.529) >0.05 女 0 10 30.0 年龄(岁) ≤60 0 54 37.0 1.184(0.600~2.339) >0.05 >60 1 17 39.2 肿瘤长径(mm) ≤50 0 27 48.1 >50 1 44 30.6 1.626(0.873~3.029) >0.05 甲胎蛋白(μg/L) <20 0 26 48.6 1.891(0.991~3.607) >0.05a ≥20 1 45 31.1 乙型肝炎表面抗原 阴性 0 11 31.8 0.905(0.404~2.030) >0.05 阳性 1 60 38.3 乙型肝炎e抗原 阴性 0 50 37.1 0.982(0.515~1.871) >0.05 阳性 1 21 38.1 肿瘤包膜 完整 0 36 46.2 不完整 1 35 28.6 0.573(0.318~1.033) >0.05a 肝硬化 无 0 38 30.2 0.756(0.418~1.366) >0.05 有 1 33 45.5 肿瘤数目 单个 0 63 40.7 2.211(1.024~4.777) <0.05 多个 1 8 12.5 门静脉癌栓 无 0 57 43.9 2.911(1.485~5.704) <0.05 有 1 14 8.6 微血管侵犯 无 0 46 52.2 3.899(2.115~7.186) <0.05 有 1 25 8.9 巴塞罗那临床肝癌分期(期) 0~A 1 25 52.0 1.443(0.717~2.904) >0.05 B 2 32 37.5 3.587(1.615~7.966) <0.05 C 3 14 8.6 线粒体DNA拷贝数 高 0 23 54.7 0.440(0.223~0.871) <0.05 低 1 48 29.2 注: 线粒体DNA低拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值<1,线粒体DNA高拷贝数为肝癌组织与癌旁组织的线粒体DNA拷贝数比值≥1;a0.05<P<0.10表 3 影响71例肝细胞癌病人预后的多因素分析
Table 3 Multivariate analysis of survival in 71 hepato⁃ cellular carcinoma patients
临床病理因素 b值 标准误 Wald值 风险比(91%可信区间) P值 甲胎蛋白 0.659 0.366 3.246 1.932(0.944~3.956) >0.05 肿瘤包膜 0.170 0.359 0.225 1.186(0.586~2.398) >0.05 肿瘤数目 0.479 0.423 1.279 1.614(0.704~3.700) >0.05 门静脉癌栓 0.687 0.727 0.893 1.989(0.478~8.276) >0.05 微血管侵犯 1.013 0.355 8.156 2.754(1.374~5.521) <0.05 巴塞罗那临床肝癌分期 -0.083 0.399 0.043 0.921(0.421~2.012) >0.05 线粒体DNA拷贝数 -0.827 0.386 4.589 0.437(0.205~0.932) <0.05 -
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