It is one of the earliest myogenic markers, both in heart and somites, and is expressed in satellite stem cells and replicating myoblasts.
AIDS, CHF, COPD Deficiency Secondary myoadenylate deaminase deficiency Myopathies due to disturbance in carbohydrate metabolism The glycogen storage diseases GSD are a group of inborn error of metabolism characterized by glycogen accumulation in tissues due to enzyme defects in the glycogenolytic or glycolytic pathways.
Among the glycogen storage diseases some present as pure myopathy, whereas others involve other Myofibrillar myopathy like liver or RBCs. When an enzyme defect affects mainly glycogen storage in liver, a common symptom is hypoglycemia. When the defect is in the muscle tissue, weakness and exercise intolerance result from defect in the glycolytic pathway.
These glycolytic pathway enzymes are found in cytoplasm, endoplasmic reticulum and lysosomes. Some enzymes Myofibrillar myopathy specific to individual organs. All the GSDs are inherited as autosomal recessive trait except phospho-glycerokinase deficiency, which is inherited as X-linked recessive disorder.
The most important GSDs from clinical standpoint are acid maltase deficiency and myophosphorylase deficiency 7.
Rarely however, may these have lactic acidosis and related muscle cramps 78. Acid maltase deficiency is a clinically heterogeneous group of diseases that has relatively distinct age of onset variants consisting of three forms viz. The infantile form presents in first few weeks to years of life with diffuse hypotonia and weakness of the muscles.
Hepatomegaly, macroglossia, cardiomegaly and early respiratory muscle involvement are common in infantile and childhood varieties.
Infantile form is fatal before 2 years of age. The childhood and adult forms of acid maltase disease are primarily the disorders of skeletal muscle. They present as slowly progressive muscle weakness associated with calf hypertrophy, which bears close resemblance with Duchenne's muscular dystrophy 9 GSD II primarily involves skeletal and cardiac muscles.
The deficient enzyme is "acid alpha-1, 4-glucosidase" glucan 1,4-alpha-glucosidase or acid maltase.
This enzyme is present in lysosomes and catalyzes the hydrolysis of the glycogen into glucose. These inclusions disrupt the normal functions of the muscle cell and eventually the cell dies.
When muscle cells are injured, their contents spill into the blood 10 Biochemical findings Deficiency of alpha-glucosidase activity can be demonstrated in muscle fibers, fibroblasts, leukocytes, lymphocytes and urine. Severe deficiency of alpha-glucosidase activity occurs in infantile form but residual activity is observed in the less severe adult onset form.
Serum creatine kinase CK levels are elevated in rill forms of the disease but to variable degree. The infantile form is associated with the highest CK levels, but these levels are often less than 10 times the upper limit of normal. In adults, the CK level can be normal. Thus serum CK levels may be useful in differentiating this disorder from closely mimicking Duchenne muscular dystrophy 9, 11 and Histopathology On light microscopy, vacuoles are seen within type -I and II fibers.
The vacuoles are most prominent and more uniformly seen in nearly all the muscle fibers in the infantile form. These vacuoles react strongly with periodic acid-Schiff stain, which is sensitive to diastase.
The vacuoles also stain intensely to acid phosphates, confirming that the vacuoles filled with glycogen are secondary lysosomes. Electron microscopic study shows abnormal accumulation of glycogen in lysosomes as well as cytoplasm.General Marked variation in severity within families Anticipation.
Mean symptom onset 29 years earlier in child compared to parent; Due to tendency of GTG repeat to enlarge when transmited from 1 . Myofibrillar myopathy is a muscular disease and part of a group of disorders called muscular dystrophies.
The condition is characterized by improper functioning of muscle fibers causing weakness. Progressive muscle weakness. Limb-girdle (proximal) weakness. Chronic. Drug/toxin-induced myopathy: The following drugs may give rise to myopathy chlorquine, clofibrate, colchicine, AZT, vincristine, alcohol, corticosteroids and statins.
Toxic oil syndrome due to adulterated rapeseed oil also cause inflammatory myopathy in addition to inflammatory polyneuropathy. Desmin-related myofibrillar myopathy is a subgroup of the myofibrillar myopathy diseases and is the result of a mutation in the gene that codes for desmin which prevents it from forming protein filaments, instead forming aggregates of desmin and other proteins throughout the cell.
Engel et al. () first reported multiminicore myopathy in 2 affected sibs. The disorder was a congenital myopathy associated with multifocal degeneration of muscle fibers on pathologic examination. Swash and Schwartz () reported 2 brothers and a sister with a congenital myopathy characterized clinically by proximal weakness and external ophthalmoplegia and histologically by multicores.
Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms.
Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression in individuals, but all share.