1, the current research results of myotonic dystrophy and genetics: myotonic dystrophy is a group of genetic diseases, genetic diagnosis is very important to confirm the diagnosis. At present, for the most common types of myotonic dystrophy such as DMD, BMD, ankylosing myotonic dystrophy, etc., limb-girdle myotonic dystrophy genetic testing has been commercialized, and commonly used genetic examination methods include multiplexed probe amplification technology (MLPA), denaturing high performance liquid chromatography (DHPLC), fragment analysis (FA), Sanger sequencing and new generation high-throughput sequencing technology. Different technologies are suitable for detecting different types of mutations, and determining the possible type of myotonic dystrophy based on the patient’s clinical manifestations, blood biochemical changes, and skeletal muscle pathological changes, and selecting the appropriate testing method can improve the testing efficiency, save labor and material resources, and also save the testing cost for the patient’s family. In 60%-70% of patients with DMD/BMD, the causative mutation is a deletion or duplication of one or more exons, so MLPA or DHPLC is the preferred genetic testing method when the clinical diagnosis of DMD/BMD is made; if no deletion or duplication mutation is found after testing, point mutation detection by sequencing methods, or pathological, immunohistochemical staining can be considered. immunohistochemical staining to help determine the next step of genetic testing. Fragmentation methods are used to detect dynamic mutations in trinucleotide repeat sequences and are suitable for the genetic diagnosis of ankylosing myotonic dystrophy types 1 and 2. Limb-girdle muscular dystrophy is complex, and the typing based on pathogenic genes has been divided into more than 20 subtypes 1A-1H and 2A-2S, among which the most common are type 2A caused by gene mutations and type 2B caused by Dysferlin (DYSF) gene mutations, and the pathogenic gene of each subtype contains many exons, and the mutation types are mainly point mutations, which are suitable for the use of The new generation high-throughput sequencing method was used to screen for disease-causing mutations. When screening for mutations by high-throughput sequencing, many mutations can be obtained, which should be closely combined with clinical manifestations and family analysis to carefully determine whether the mutations are pathogenic or normal polymorphisms, and not to misclassify genetic polymorphisms in the population as pathogenic mutations. The most specific mutation in facial scapulohumeral muscular dystrophy (FSHD) is a polymorphic giant satellite repeat sequence abnormality on chromosome 4. The copy number of the 3.3-kb repeat unit (D4Z4) on both chromosomes of normal individuals is 11-100, while the copy number of one chromosome is reduced to 1-10 in the majority of FSHD patients. The genetic testing of FSHD is to measure the length of this D4Z4 repeat sequence, which requires multi-locus Southern hybridization based on pulsed field gel electrophoresis (PFGE), and only a very few research units in China can perform the test. 2, the role of gene positioning for clinical diagnosis and treatment of myotonic dystrophy: clinical work, when we consider the diagnosis of myotonic dystrophy through clinical manifestations, medical history and physical examination, laboratory tests (sometimes including muscle biopsy), we will recommend patients to do genetic examination to determine the diagnosis, the most common question asked by patients at this time is: “After doing the genetic examination my disease can be Can I be cured?” Genetic test is first of all a diagnosis method rather than a treatment method, and the current situation in China is that most of the patients with myotonic dystrophy cannot be cured even if the causative gene mutation is clarified in time. However, genetic diagnosis is of irreplaceable importance to the clinical diagnosis and treatment of myotonic dystrophy. Take DMD as an example, if a patient has a clear family history of X-linked recessive inheritance, a family with previous patients who died before the age of 20, and typical clinical symptoms, signs and biochemical and electrophysiological changes, it is highly suggestive of DMD diagnosis, and usually we do not do invasive muscle biopsy, but directly recommend genetic examination. Through genetic examination to clarify the site of the patient’s gene mutation, first of all, when the targeted gene therapy methods into clinical application, patients with clear causative genes can be the first to benefit; secondly, it is possible to diagnose carriers in the family, female first-degree relatives of DMD patients and female members of the mother’s family may be carriers, including their mothers, sisters, aunts, aunt cousins, etc., if these may be If these family members who may be carriers are in their childbearing years, the determination of the identity of the carrier is more important, according to the law of X-linked recessive inheritance, DMD female carriers combined with normal males, may give birth to normal males, normal females, female carriers or male patients, the odds of each account for 25%, the carrier pregnancy if the fetus is determined to be male, prenatal diagnosis must be performed, and clear patient gene mutation is to carry out the carrier The mutation is the basis for prenatal diagnosis of carriers; the daughter of a BMD patient must be a carrier, and once the type of mutation is clarified, the subsequent prenatal diagnosis can be guided. In some autosomal dominant subtypes of myotonic dystrophy, such as ankylosing myotonic dystrophy and autosomal dominant limb-girdle myotonic dystrophy, the chance of having a child with the disease is as high as 50%, and it is important to clarify the genetic diagnosis so that a prenatal diagnosis can be made. Even in autosomal recessive subtypes, a definitive genetic diagnosis is necessary to prevent patients from blindly seeking medical help and trying “treatments” that have no scientific basis. Certain types of myotonic dystrophy can be treated based on genetic diagnosis to improve the quality of life and prolong the life span of patients, and to lay the foundation and buy time for future gene therapy; by clarifying the genetic mutation of patients, prenatal diagnosis can be conducted to prevent the birth of patients in the family and to avoid the recurrence of tragedies. In the treatment of myotonic dystrophy, doctors are not only dealing with one patient but also one family. From this perspective, it is easy to understand the importance of gene diagnosis for clinical diagnosis and treatment of myotonic dystrophy.