General Information The term "muscular dystrophy" incorporates an assortment of hereditary disorders that lead to progressive, generalized disease of the muscle prompted by inadequate or missing glycoproteins in the muscle cell plasma membrane. Muscular dystrophy is a non-communicable disorder with abundant variations. Each has its pattern of inheritance, onset period, and the rate at which muscle is lost. Alterations in specific genes cause different representations of this disease. Anatomy Research has established that the gracilis, semimembranosus, semitendinosus, and sartorius muscles can be affected in patients with muscular dystrophy. Feet can exhibit an equinovarus deformity. The pelvis can tilt. There may be contractures throughout the body. Spinal deformities may produce lordosis or scoliosis. The eye can exhibit cataracts and bilateral ptosis. Natural History Onset usually occurs in the third to fourth decades. But, it may reveal in infancy or undergo accelerated deterioration near the age of onset. Parents of affected individuals may present concern that their child is not walking as well as other children their age. The child may have trouble kicking a ball due to weakness. Pseudo-drop events caused by weakness of quadriceps muscle may also be present. Both parents could be healthy. On physical examination, the affected individual will have massive calf muscles plus lower limb proximal muscle weakness. This condition will make affected individuals want to utilize their arms and hands to aid in rising from a seated position. Other complaints can involve a history of delayed ambulation, toe walking, calf hypertrophy, and proximal hip girdle muscle instability. Presentations may also incorporate asymptomatic elevation of serum creatine kinase (CK), exertion intolerance, dilated cardiomyopathy, malignant hyperthermia, quadriceps myopathy, language delay, and Turner syndrome (Duchenne in X chromosome monozygotic females). For some with subclinical muscular dystrophy, the diagnosis is initially suspected by family history or the appearance of raised liver enzymes, the basis for which is unclear. These enzymes may include alanine aminotransferase and aspartate aminotransferase. Since the inheritance of muscular dystrophy can be X-linked, the overwhelming majority of patients are male. Symptomatic disease in daughters is explainable by Turner syndrome, skewed X chromosome inactivation, translocation of the mutated gene to an autosome, or uniparental disomy (both copies of a chromosome set originated of one parent). Usually, symptomatic females present in infancy with proximal muscle weakness. Reports exist of increased weakness in adulthood, myalgias, spasms, and lethargy as initial manifestations. Scoliosis and sustained alveolar hypoventilation can cause severe problems for every child with muscular dystrophy. Patterns of Spread Muscular dystrophy can be caused by mutations in numerous genes and can be transferred in an X-linked, autosomal dominant, or autosomal recessive fashion. Changes in the X-linked gene DMD, which encodes dystrophin, is the most frequent cause of muscular dystrophy. This why the phenotype is manifested in hemizygous males because they have only a single copy of the X chromosome. One should note that mutations in dystrophin also create allelic heterogeneity. Mutations in the DMD gene, for example, may cause muscular dystrophy of both Duchenne or the less serious Becker, based on the extent of the lack of protein. Although the phenotypic characteristics of some of these disorders are definite, the phenotypic spectrum produced by mutations in various genes overlaps, whereby spanning to nonallelic heterogeneity. Identification of nonallelic heterogeneity is critical for specific reasons: (1) the capacity to recognize disease loci in linkage studies is decreased by introducing subjects with associated phenotypes, but separate genetic disorders; (2) genetic testing is further complicated because several distinct genes need to be analyzed along with the likelihood of distinctive mutations in all of the candidate genes; and (3) data is concerned about how genes or proteins associate, therefore providing novel insights inside cell molecular physiology. Phenocopies are thus produced, which are incidents in which nongenetic diseases simulate a genetic disorder. For instance, features of virus or toxin-induced neurologic symptoms can mirror those seen in muscular dystrophy. As in nonallelic heterogeneity, phenocopies continue to confound linkage studies and genetic testing. Patient history and accurate differentiation in phenotype can usually render signs that differentiate these maladies from similar genetic diseases. It is important to note that muscular dystrophy has variable expressivity and incomplete penetrance and, therefore, may be combined over a phenotypic spectrum in various affected individuals, further demonstrating the aspect of variable expressivity.