Abstract:

Objective To investigate the mitochondrial DNA (mtDNA) mutation load in hair follicles from different scalp regions of patients with mitochondrial, encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), compare the mutation load in different scalp regions, and analyze the difference in mutation load between scalp regions with lesion site in the brain and scalp regions without lesion site in the brain. Methods  Seven MELAS patients with m.3243A > G mutations were studied. Hair follicles were obtained from 8 scalp regions (bilateral frontal, temporal, parietal and occipital lobes) of all patients and DNA was extracted. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to detect the m.3243A > G mutation. Results  The mean value of m.3243A > G mutation load in hair follicles from all patients was (60.57 ± 7.71)%. In different scalp regions, the mean mutation load was (61.30 ± 7.32)% in left frontal, (65.41 ± 5.85)% in right frontal, (59.80 ± 5.58)% in left temporal, (57.59 ± 14.47)% in right temporal, (62.46 ± 5.02)% in left parietal, (60.11 ± 7.11)% in right parietal, (59.70 ± 8.68)% in left occipital and (59.42 ± 6.28)% in right occipital regions, respectively. There was no significant difference in the m.3243A > G mutation load among different scalp regions (F = 0.537, P = 0.802). There was no significant difference in the mutation load between scalp regions corresponding lesion site of the brain and scalp regions incorresponding lesion site of the brain [(60.33 ± 8.70)% vs. (61.02 ± 6.52)%; t = 0.319, P = 0.751)]. Conclusions Hair follicles are convenient and noninvasive sampled tissue for detecting mtDNA mutations. There is no difference in the mutation load among different scalp regions. Furthermore, there is no difference between scalp regions corresponding lesion site of the brain and scalp regions incorresponding lesion site of the brain.

Key words: MELAS syndrome, Hair follicle, DNA, mitochondrial, Mutation

摘要：

目的 比较线粒体脑肌病伴高乳酸血症和卒中样发作（MELAS）患者头皮不同区域毛囊线粒体DNA（mtDNA）突变率的差异，并探讨其与脑卒中样发作累及皮质病灶的关系。方法 采集7 例MELAS 患者8 个头皮区域（双侧额叶、颞叶、顶叶、枕叶）毛囊DNA，聚合酶链反应-限制性片段长度多态性检测m.3243A > G 突变率。结果 7 例患者8 个头皮区域毛囊m.3243A > G 突变率为（60.57 ± 7.71）%，左侧额叶、右侧额叶、左侧颞叶、右侧颞叶、左侧顶叶、右侧顶叶、左侧枕叶、右侧枕叶分别为（61.30 ±7.32）%、（65.41 ± 5.85）%、（59.80 ± 5.58）%、（57.59 ± 14.47）%、（62.46 ± 5.02）%、（60.11 ± 7.11）%、（59.70 ±8.68）%、（59.42 ± 6.28）%，各区域差异无统计学意义（F = 0.537，P = 0.802）。脑卒中样发作病灶对应头皮区域与非病灶对应头皮区域毛囊m.3243A>G 突变率差异亦无统计学意义［（60.33 ± 8.70）%对（61.02 ±6.52）%；t = 0.319，P = 0.751］。结论 头皮毛囊是方便易取、无创性组织标本，可用于mtDNA 突变检测。MELAS 患者不同头皮区域毛囊mtDNA 突变率无差异，脑卒中样发作病灶对应头皮区域与非病灶对应头皮区域毛囊mtDNA 突变率亦无差异。

关键词: MELAS综合征, 毛囊, DNA, 线粒体, 突变