What is myotonic dystrophy: Myotonic dystrophy, also known as progressive myotonic dystrophy, is a group of muscle degenerative diseases caused by genetic factors. The name “myotonic dystrophy” is easily misunderstood by lay people who believe that this group of diseases is related to nutrition, but in fact the onset of myotonic dystrophy is not related to nutrition, nor can it be cured by supplementation. To establish a correct understanding of this group of diseases, let’s take a look at its English name: The key word here is dystrophy, we know that dys- this root word means bad, abnormal, and -trophy is the meaning of proliferation, growth, so it refers to poor muscle growth, and nutrition (nutrition) is not directly related. So, why would skeletal muscle cells be “stunted”? We know that skeletal muscle is the most laborious group in the human body, there are more than 600 skeletal muscle, accounting for 40% of body weight, its function is to contract and diastolic according to the instructions of motor neurons, producing skeletal movement. The skeletal muscles in different parts of the body vary in shape and size, and are adapted to their functions. There are multiple protein components on the surface of skeletal muscle cells, in the cell membrane, in the cytoplasm, and in the nucleus, which are closely linked structurally and functionally and work together to maintain the stability of skeletal muscle cells so that they are not damaged during repeated contraction and diastole activities. When the genes encoding these proteins are mutated, resulting in reduced or absent expression of the corresponding proteins, the skeletal muscle cells lose their stability and gradually degenerate and die, leading to myotonic dystrophy. Currently, many subtypes of myotonic dystrophy have been identified with the causative genes and their encoded protein components, while some types of myotonic dystrophy are caused by mutations in non-coding regions, the associated protein components of which have not been identified, and some have not been identified with their mutation loci. Pathology of myotonic dystrophy: Classical pathological changes in myotonic dystrophy include skeletal muscle cells of uneven size, degeneration, necrosis, and rounding of muscle fibers, hyperplasia of interstitial connective tissue, increased adiposity, and phagocytosis and regeneration of myocytes. The pathologic changes of clinical muscle biopsy in specific patients are related to the stage, extent, and sampling site of the lesion, and some types of myotonic dystrophy have other characteristic pathologic manifestations in addition to the above-mentioned myotonic changes. Currently, clinical muscle biopsies emphasize the selection of sampling sites and standardized frozen sections, formal histochemical staining, enzyme histochemical staining, and immunohistochemical staining for specific protein components are of diagnostic significance for certain subty of myotonic dystrophy. Epidemiology: Each specific type of myotonic dystrophy is a rare disease, and epidemiological statistics vary considerably from region to region. The prevalence of the more studied Duchenne muscular dystrophy (DMD) is 1/3500 live births in male infants. The level of diagnosis of myotonic dystrophy varies among different medical institutions in China, and underdiagnosis and misdiagnosis are common, and there is no exact epidemiological data published. There are various systems for classifying myotonic dystrophy: DMD, Beker muscular dystrophy (BMD), Miyoshi muscular dystrophy, Emery-Dreifuss muscular dystrophy (EDMD), etc., named after the person who first reported them; according to the age of onset, there are those with onset within 1 year of age or even during fetal life, children and adolescents, early adulthood, and adulthood, each with corresponding subtypes; according to the age of onset, there are those with onset within 1 year of age or even during fetal life, children and adolescents, early adulthood, and adulthood. According to the distribution of affected muscles, they are divided into pseudohypertrophy, facioscapulohumeral, limb-girdle, distal, oculopharyngeal, and distal oculopharyngeal types, etc.; according to the causative genes, they can be divided into dystrophinopathy (including DMD, BMD, etc.), dysferlinopathy (including limb-girdle dystrophy type 2B and Miyoshi distal dystrophy), calpainopathy (limb-girdle dystrophy type 2B and Miyoshi distal dystrophy), and dystrophinopathy. calpainopathy (limb-girdle muscular dystrophy type 2A) Sarcoglyconopathy (including limb-girdle muscular dystrophy type 2C-2F), etc.; according to the mode of inheritance, it is divided into X-linked recessive inheritance (DMD, BMD, EDMD), autosomal dominant inheritance (including limb-girdle muscular dystrophy type 1, ankylosing muscular dystrophy, some distal muscular dystrophy dystrophy), autosomal recessive inheritance (including limb-girdle dystrophy type 2, congenital myotonic dystrophy, etc.). With the increasing popularity of genetic diagnosis, more and more patients can be diagnosed at the molecular biology level, and it is the future trend to classify the disease according to the causative genes. Clinical manifestations of myotonic dystrophy: The common manifestations are slow onset, progressive muscle weakness and myasthenia gravis. Some subtypes have characteristic distribution patterns of affected muscle groups (e.g., facioscapulohumeral, oculopharyngeal, distal muscular dystrophy, etc.), and some have characteristic concomitant symptoms, such as DMD, BMD and some types of limb-girdle muscular dystrophy with pseudohypertrophy of the gastrocnemius muscle, ankylosing muscular dystrophy with myotonicity, early joint contracture in EDMD, and some congenital muscular dystrophy with central nervous system. Some congenital myotonic dystrophy is associated with central nervous system abnormalities, and some subtypes of myotonic dystrophy may be associated with early cardiac and respiratory muscle involvement. It is important to note that the clinical manifestations of the same subtype can vary greatly from patient to patient, and even in the same family, the degree of involvement can vary from patient to patient. Risk factors for myotonic dystrophy: As a group of hereditary diseases, the risk factors for myotonic dystrophy include the history of consanguineous marriage in the family and the presence of myotonic dystrophy in relatives, which should be analyzed in the context of the specific causative genes and mode of inheritance. Also, regardless of the mode of inheritance of the disease, there can be epidemic cases due to de novo mutations.