Mitochondrial diseases are a relatively common and complex group of genetic disorders that arise from defects in mitochondrial metabolic enzymes caused by genetic abnormalities. The pathogenesis of mitochondrial diseases is mainly due to nuclear gene defects, mitochondrial gene defects and impaired signaling between MtDNA and nuclear genes, resulting in impaired substrate transport or utilization, impaired protein transport, impaired tricarboxylic acid cycle, impaired oxidative phosphorylation coupling and defective respiratory chain, causing impaired adenosine triphosphate synthesis, increased oxygen free radicals, intracellular redox imbalance and induction of apoptosis, and ultimately multisystem damage. The observation of clinical conditions, design of ancillary tests and treatment arrangements need to be centered on the pathophysiological process of the disease. The clinical data of mitochondrial disease patients should be collected with attention to the order of symptoms and signs of each system. Some relatively common symptoms caused by mitochondrial lesions in the nervous system should be noted, such as seizures, extraocular muscle paralysis, visual impairment, seizure encephalopathy, hearing loss, ataxia, vestibular dysfunction, dystonia, migraine, psychomotor regression, dementia, and other systemic manifestations, such as short stature, diabetes mellitus, heart block or cardiomyopathy, pseudo-intestinal obstruction or liver failure in the digestive system, and renal disease. and kidney disease. The appearance of these signs or symptoms varies greatly among different types of mitochondrial disease, and can manifest as single system or organ disease, such as mitochondrial myopathy, peripheral neuropathy, encephalopathy, diabetes mellitus, cardiomyopathy, deafness, optic neuropathy, or as multi-system or multi-organ damage disease, such as mitochondrial encephalomyopathy, gastrointestinal encephalomyopathy, and some types can be further classified as MtDNA loss mutation syndrome Some types can be further classified as MtDNA loss mutation syndrome or MtDNA deletion mutation syndrome or other specific gene mutation spectrum diseases, and it should be noted that some patients have several syndromes overlapping at the same time. So far, more mitochondrial diseases have been diagnosed in China, and the clinical manifestation characteristics of different mitochondrial disease subtypes in China should be summarized in conjunction with different clinical departments. Second, the rational application of relevant examination techniques Mitochondrial disease needs to be diagnosed by different auxiliary examination methods, including those for patients and their family members, such as the rational use of electrophysiological, biochemical, imaging, pathological and genetic examinations in combination with the possible types of patients, etc. Special attention should be paid to the problem of sensitivity and specificity of any one method in use, and the interpretation of results needs to consider the Inadequacies. 1, electrophysiological examination: patients found to have brain and heart abnormalities need to undergo EEG and ECG, the results of which are not specific, but can help to observe the development of heart and brain damage in regular follow-up. 2, biochemical examination: standardized lactate pyruvate minimum motility test has high specificity for mitochondrial myopathy, but poor sensitivity; fibroblast growth factor 21 can be used as a sensitive marker for screening, but specificity needs further verification; mitochondrial respiratory chain enzyme complex subunit activity assay is a reliable method to check mitochondrial function, taking fresh tissue or cultured fibroblasts for It is only used for the diagnosis of some mitochondrial disease subtypes. 3.Imaging: MRI of the head is used to examine brain damage in patients with mitochondrial encephalopathy or encephalomyopathy, but similar imaging changes can be seen in immune, infectious, circulatory, and other metabolic diseases. 4.Pathological examination: mainly muscle biopsy is used only for mitochondrial disease subtypes accompanied by skeletal muscle damage. Mitochondrial hyperplastic changes in muscle fibers or blood vessels found in frozen sections can be considered only after ageing and secondary changes from other diseases are excluded. 5, genetic examination: all types of mitochondrial disease require genetic examination to assist in the diagnosis. In patients with defects in the respiratory chain enzyme complex found by biochemical examination, whole exome examination has high application for the detection of nuclear mutations in mitochondrial disease. It should be noted that mtDNA mutation rates vary widely across tissues, and different methods of examination are required depending on the mode of mutation. Negative test results may be related to inappropriate specimens taken or genetic examination methods, and need to be re-examined with other tissues or examination methods if necessary. How to determine whether a mutation is pathogenic requires not only conforming to the general pattern of pathogenic gene mutations, but also determining whether it is a secondary mtDNA mutation accompanying aging or other diseases. The mtDNA pathogenic mutations without typical clinical manifestations are mtDNA mutation carriers and should be followed up and observed. Third, perfect treatment strategy There is no specific drug for the treatment of mitochondrial disease so far, and it is important for patients or gene carriers to discover and eliminate the external factors leading to the development of the disease to stop the occurrence and progression of the disease. The basic therapeutic principle is to maintain an adequate diet to maintain the balance and stability of energy metabolism. It is important to regulate dietary rhythms in conjunction with digestive and physiological processes, to arrange multiple meals a day, to conduct a high-fat, low-sugar diet, to give a ketogenic diet in patients presenting with refractory epilepsy, and generally not to over-activate or use the brain in a fasted or starved state to prevent the induction of metabolic crises. Smoking and heavy alcohol consumption can exacerbate the development of mitochondrial disease, and acute onset may result from inappropriate medication in the presence of other diseases in the patient, as many drugs are mitochondrial toxic. Patients undergoing general anesthesia should take special care to avoid metabolic disturbances and metabolic acidosis. There is a lack of drug studies for mitochondrial disease in our country. Drug therapy needs to be combined with the results of enzyme complex activity assays. The use of drugs for mitochondrial disease as a rare disease needs to be explored in the context of the latest research findings, and the effect of combining drugs for multiple pathways needs to be confirmed in clinical studies. To improve the quality of life of patients, non-pharmacological treatments such as cochlear implantation in deaf patients when hearing aids are not effective, frontalis suspension surgery in patients with ptosis, pacemaker placement in patients with severe heart block, implantable cardioverter-defibrillators in patients with ventricular tachycardia, and heart transplantation in patients with severe cardiomyopathy should be emphasized. The course of mitochondrial disease varies greatly between subtypes, and the management of each subtype varies widely. It is important to be aware of the possibility of rapid changes at any time in some types and slow progression in others, and to be alert for insidious development of respiratory and cardiac failure. In both early diagnosis or follow-up, attention should be paid to early correction of energy imbalances to avoid metabolic crises. The rarity of mitochondrial disease and the complexity and variability of the condition dictate that its treatment needs to be addressed within a highly specialized medical team, and that individualized and precise treatment is ideal for the management of mitochondrial disease with a view to achieving better control.