线粒体疾病

线粒体疾病的症状是什么？

由于线粒体在人体的每个细胞中，因此线粒体疾病会影响许多不同的身体系统，并在不同组合中引起多种症状。这可以使他们具有挑战性地诊断。

人体往往受到最大影响的部分是那些需要最多能量的人，例如心脏，大脑，肌肉和胃肠道。症状可能从疲劳和运动不耐受到听力丧失，癫痫发作，中风，心力衰竭，糖尿病和肾衰竭。绝大多数但并非所有患有线粒体疾病的儿童都有发育迟缓。

Depending on the severity of the disorder, symptoms can appear at birth or they may not appear until adulthood. In some children, mitochondrial disease progresses quickly and can be severe. In others, it can be stable and well-managed for many years. Sometimes symptoms begin suddenly, triggered by another illness.

What causes mitochondrial disease

Mitochondria are the “power plants” of all the cells in the human body, producing the energy our bodies need to function. They are also involved in metabolism, helping our cells build, break down and recycle compounds they need.

在线粒体紊乱,线粒体的ability to do these jobs is impaired because of a genetic mutation — a “mistake” in the DNA. We all have two types of DNA in our bodies. The nuclear DNA (usually just called “DNA”) is found in the cell's nucleus and is inherited from both our mother and father. Mitochondria also have DNA, inherited from mothers. Because both types of DNA are responsible for the structure and function of the mitochondria, mutations in either can cause mitochondrial disorders. Mutations can be inherited from parents or can happen for the first time in a child (so-called从头mutations).

Inherited mutations in the mitochondrial DNA come from the mother. Mutations in nuclear DNA usually are recessive, meaning that one copy of the mutation comes from each parent. In this case, the parents are just carriers and do not have mitochondrial disease themselves. This also explains why some people with a mitochondrial disorder have a family history of the disorder, while others are the only one in their family to be affected.

For more on mitochondrial disease, visit our常见问题页面。

线粒体疾病如何诊断？

Because症状are so varied, affecting multiple organs in the body, diagnosing mitochondrial disease can be challenging. Sometimes other disorders not involving the mitochondria are mistakenly diagnosed as mitochondrial disease. The opposite is true as well: Sometimes individuals who truly have mitochondrial disease are diagnosed as having something else.

许多症状线粒体疾病（例如未能繁殖，身材矮小，耐力差，发育延迟，癫痫发作，肌肉张力差，呕吐，严重的便秘或腹泻）都有多种其他原因。因此，它通常不是一个症状，而是两种，三个或更多不同的症状的组合，导致临床医生怀疑线粒体疾病。

Genetic testing is the most reliable way to diagnose and categorize a mitochondrial disorder. We may recommend genetic testing for your child (and sometimes for parents too) if any of these symptoms are present:

• developmental delay with involvement of other organs
• dardiomyopathy (disease of the heart muscle) or unexplained heart block, or impaired electrical signals in the heart
• high levels of lactate in the blood or cerebrospinal fluid, when other symptoms are present
• 大脑成像的某些异常发现
• ophthalmoplegia (impaired eye movement) or ptosis (drooping upper eyelid)
• 听力损失
• 严重的胃肠道不动障碍（肠道中的弱或肌肉收缩）或肠道伪腹部（肠梗阻是由于肠道无法将食物推开而引起的肠梗阻）
• 在疾病环境中的重大发展回归

基因测试通常始于分析线粒体DNA，如果结果为阴性，则测试核DNA是否已知参与线粒体疾病的基因。如果这些测试呈阴性，则可能需要通过整个外显子组测序对孩子的核DNA进行完全分析（这类似于整个基因组测序，但仅分析了为蛋白质编码的基因）。

我们建议的基因测试的类型和深度将取决于孩子的症状以及我们怀疑线粒体疾病的强烈强烈。不幸的是，在撰写本文中，保险并不总是涵盖广泛的基因检测。如果您或您的孩子需要测试，我们将与您的保险公司合作，以帮助批准。

Additional, non-genetic tests also help in diagnosing mitochondrial disorders. They include:

• biochemical tests on urine, blood and spinal fluid
• 肌肉活检检查线粒体和测试酶水平
• magnetic resonance imaging (MRI)of the brain and spine

If a mitochondrial disorder is suspected or identified, we may refer your child for further testing and consultations with specialists. Testing depends on symptoms, and may include:

• echocardiogram
• 心电图（EKG）
• eye examinations
• hearing tests

管理孩子的状况

虽然线粒体疾病无法治愈，但当症状被发现并提早解决时，孩子通常会做得更好。您的孩子将受到仔细的遵循，并筛查与线粒体疾病有关的各种疾病，例如心脏，视力和听力问题。通常可以通过保持良好的一般健康来缓解症状，包括仔细注意营养以及避免感染和脱水。

Exercise is one of the few proven methods for improving mitochondrial functioning and can help preserve your child’s strength and endurance. Exercise regimens should be supervised, should build up very gradually in intensity and should be suspended during illness.

What are the treatment options for mitochondrial disorders?

Currently, vitamins and supplements are the mainstay of treatment for mitochondrial disorders. They are thought to help mitochondria produce energy and reduce accumulation of toxic compounds inside cells. These supplements and cofactors are sometimes given together in “cocktails.” At present, the compounds that have been most well tested include coenzyme Q10 and creatine, but we also use a great variety of other supplements.

Regimens for specific mitochondrial disorders may include compounds that are deficient because of the disease, such as arginine (in MELAS) and folinic acid (in Kearns-Sayre syndrome). At Boston Children’s, we are testing dichloroacetate (DCA), which counters the high levels of lactic acid found in some mitochondrial disorders. In certain disorders, we may prescribe a special diet.

支持护理

Because children with mitochondrial disease tend to be very sensitive to the stresses caused by minor illnesses like colds and fevers, your clinician will sometimes prescribe additional supportive therapies when the child is sick. These can include vitamins, cofactors, medications to counter biochemical imbalances that may occur, beverages containing electrolytes and sometimes intravenous (IV) hydration and IV antibiotics. In some instances, your child may need to be monitored in the hospital.

Children with mitochondrial disease also are known to be sensitive to a variety of drugs, as well as anesthetics used for surgical procedures.