Progress in the mechanism of estrogen receptors in skeletal muscle diseases / 国际儿科学杂志

Estrogen receptors are steroid receptors, widely distributed in skeletal muscle, liver and other tissues.Currently, there are 5 known estrogen receptors.Different estrogen receptors are distributed in different places and have different functions.By mediating different estrogen receptors, estrogen plays an important role in anti-inflammation, promoting proliferation and inhibiting muscle atrophy.Skeletal muscle is the main tissue in the human body, accounting for about 40% of body weight.Skeletal muscle not only plays the role of exercise and support, but also plays an important role in maintaining the body′s metabolism.In recent years, estrogen receptors have received extensive attention in skeletal muscle diseases.Estrogen receptors are considered as potential targets for the treatment of skeletal muscle diseases such as Duchenne muscular dystrophy(DMD)and myotubular myopathy(MTM). This article reviews the research progress of estrogen receptors in skeletal muscle diseases.

Two Cases of X-Linked Myotubular Myopathy with Novel MTM1 Mutations

BACKGROUND: Myotubular myopathy (MTM) is a congenital myopathy characterized by centrally placed nuclei in muscle fibers. Mutations in the myotubularin 1 gene (MTM1) have been identified in the most of the patients with the X-linked recessive form. CASE REPORT: This report describes two male infants with X-linked MTM (XLMTM). Both patients presented with generalized hypotonia and respiratory difficulties since birth. We did not perform a muscle biopsy in either patient, but their conditions were diagnosed by genetic testing of MTM1. One splicing mutation, c.63+1G>C, and a frame-shift mutation, c.473delA (p. Lys158SerfxX28), were identified. Neither mutation has been reported previously. CONCLUSIONS: Genetic testing for MTM1 is helpful for the differential diagnosis of floppy male infants. We suggest that advanced molecular genetic testing may permit a correct diagnosis while avoiding invasive procedures.

X-linked recessive myotubular myopathy with MTM1 mutations / 소아과

X-linked recessive myotubular myopathy (XLMTM) is a severe congenital muscle disorder caused by mutations in the MTM1 gene and characterized by severe hypotonia and generalized muscle weakness in affected males. It is generally a fatal disorder during the neonatal period and early infancy. The diagnosis is based on typical histopathological findings on muscle biopsy, combined with suggestive clinical features. We experienced a case of a newborn who required intubation and ventilator care because of profound hypotonia and respiratory difficulty. The preliminary diagnosis at the time of request for retrieval was hypoxic ischemic encephalopathy, but the infant was clinically reevaluated for generalized weakness and muscle atrophy. Muscle biopsies showed variability in fiber size and centrally located nuclei in nearly all the fibers. We detected an MTM1 gene mutation of c.1261-1C>A in the intron 10 region, and diagnosed the neonate with myotubular myopathy. The same mutation was detected in his mother.

X-linked Myotubular Myopathy in a Family with Two Infant Siblings: A Case with MTM1 Mutation

X-linked myotubular myopathy (XLMTM) is a rare congenital muscle disorder, caused by mutations in the MTM1 gene. Affected male infants present severe hypotonia, and generalized muscle weakness, and the disorder is most often complicated by respiratory failure. Herein, we describe a family with 2 infants with XLMTM which was diagnosed by gene analysis and muscle biopsy. In both cases, histological findings of muscle showed severely hypoplastic muscle fibers with centrally placed nuclei. From the family gene analysis, the Arg486STOP mutation in the MTM1 gene was confirmed.

Mutation studies in x-linked myotubular myopathy in three indian families.

Congenital myopathies are a group of genetic disorders characterized by generalised muscle hypotonia and weakness of varying severity. They are distinct entities and do not include muscular dystrophies, metabolic myopathies and mitochondrial disorders. Myotubular myopathy is a rare sub type within this group of disorders. Clinical differentiation of the various types is difficult and requires muscle biopsy with histopathological and immunohistochemical studies for specific diagnosis. Gene studies are a prerequisite for genetic counseling adn prenatal diagnosis. Here presented three cases of X-linked myotubular myopathy in three Indian families where the diagnosis was established by mutation analysis in the MTM1 gene in all, and supported his histopathology in two. All three families had history of previous male neontal deaths with similar complaints. Molecular analysis revealed hemizygous mutations in the MTM1 gene including c.1261-10A>G in case, 1, c.70C>T (R24X) in case 2, and a previously unreported mutation, c.924_926delCTT(p. F308del), in case 3. Genetic counseling was performed regarding the X-linked inheritance, their 50% risk of recurrence in boys in subsequent pregnancies, and a feasibility of prenatal diagnosis. This is the first report of cases of X-linked Myotubular myopathy from India.

A Case of Adult-Onset Centronuclear Myopathy

Centronuclear myopathy (CNM) is a rare congenital myopathy that is characterized by centrally placed nuclei in the muscle fibers. Based on the time of onset and the mode of inheritance, CNM can be divided into three distinct forms: the severe neonatal form, the childhood onset form, and the adult onset form. This paper describes the case of a female patient with CNM, in whom the disease manifested itself in the fifth decade of life, without any prior family history of such disorders. To the best of our knowledge, this is a rare case of late adult-onset CNM.

A Case of Myotubular Myopathy

The term myotubular myopathy (MTM) implies a maturational arrest of fetal muscle during the myotubular stage of development at 8-15 weeks of gestation. Characteristic muscle histopathology consists of small hypotrophic muscle fibers with centrally placed nuclei and a surrounding clear area devoid of myofibrils. X-linked recessive inheritance is the most common trait. Autosomal recessive and autosomal dominant forms are less frequently reported. The clinical diagnostic criterion for X-linked MTM has relied on a positive family history and the demonstration of the presence of characteristic biopsy findings from affected male subjects. Additional features may include perinatal onset, severe hypotonia, respiratory failure, dysphagia, thin ribs, contractures of the hips or knees, puffy eyelids and ophthalmoplegia. The prognosis is often fatal, and most patients die within the first year of life from respiratory failure. The authors report a case of presumed X-linked MTM with severe hypotonia, muscle weakness and respiratory failure at birth.

Familial Myotubular Myopathy Occurred in a Sibling / 대한소아신경학회지

Myotubular or centronuclear myopathy(MTM) is a rare congenital myopathy, which is characterized by predominance and atrophy of type 1 fibers and centrally located nuclei in muscle pathology. The clinical features and severity are quite variable. MTM is classified as three forms according to the inheritance pattern : autosomal dominant, autosomal recessive and X-linked recessive. The authors present familial myotubular myopathy, suggestive of X linked, occurred in a sibling with intrafamilial clinical variability.

Myotubular myopathy: A case report

A case of a myotubular myopathy in a 5 year old boy is described. This was the first and the only boy to a 30 year old mother who had no prenatal or perinatal problems. No family history of muscle disease was present. His muscle weakness started from neonatal period but was very slowly progressive. The developmental milestones were generally delayed. He had repeated episodes of pneumonia. Muscle biopsy revealed characteristic cental nuclei in 68% of myofibers, and this findings was associated with generally small and round fibers and minimal interstitial change. No inflammatory reaction was present.