A family with dynamin 2-related centronuclear myopathy without ocular involvement

Centronuclear myopathy (CNM) is a rare congenital myopathy that is pathologically characterized by the centrally locatednuclei in most of the muscle fibers. On clinical examination, dynamin 2 (DNM2)-related CNM typically shows distaldominant muscle atrophy, ptosis, ophthalmoplegia, and contracture. The reported cases of CNM in Caucasian studies showa high prevalence rate of early-onset ptosis and ophthalmoplegia and correlated with the severity of the disease. However,Asian reports show a low prevalence and late-onset ocular symptoms in DNM2-related CNM patients. p.R465W is one ofthe most commonly found mutations in Western countries, and all the cases showed ocular symptoms. The proband and hisdaughter had no ocular symptoms despite harboring the same p.R465W mutation. This family makes us speculate that ocularsymptoms in DNM2-related CNM are influenced by ethnic background. In addition, this is the first familial case of DNM2-related CNM in Korea.

Clinical and Pathological Features of Korean Patients with DNM2-Related Centronuclear Myopathy

BACKGROUND AND PURPOSE: Centronuclear myopathy (CNM) is characterized by the presence of central nuclei within a large number of muscle fibers. Mutations of the dynamin 2 gene (DNM2) are common causes of autosomal dominant or sporadic CNM. The aim of this study was to characterize the clinical and pathological features of CNM relative to the presence of DNM2 mutations. METHODS: Six patients with clinical and pathological features of CNM were recruited. Detailed clinical and pathological findings were analyzed according to the presence of DNM2 mutations. RESULTS: We detected DNM2 mutations in four of the six sporadic CNM patients, and identified the following distinct clinical and pathological features in those patients with DNM2 mutations: preferential involvement of the distal lower limbs, typical nuclear centralization, and radially distributed sarcoplasmic strands in muscle pathology. In contrast, those without DNM2 mutations exhibited rather diffuse muscular involvement, and nuclear internalization and myofibrillar disorganization were more pronounced features of their muscle pathology. CONCLUSIONS: These findings suggest the presence of specific features in Korean CNM patients. A detailed clinical and pathological examination of CNM patients would be helpful for molecular genetic analyses of this condition.

Clinical and pathological features of 16 patients with centronuclear myopathy / 中华神经科杂志

Objective To analyze and summarize the clinical , pathological features of 16 patients with centronuclear myopathy.Methods All of the 16 patients performed clinical examination and sporadic patients and a proband with family history ( n=6 ) performed serum creatine kinase , electromyography and open muscle biopsies , and the specimens were used for a standard series of histological and histochemical stainings.The clinical and pathological features of these patients were analyzed.Results The proportion of centronuclear myopathy in suspected myopathy cases was 0.127%(6/4 724) in our department.The onset time ranged from infancy to adulthood.The common initial symptoms included mild to moderate weakness of lower limbs and bilateral ptosis ( n =4 ).The other symptoms were facial weakness ( n =1 ) and ophthalmoplegia (n=1).There were 12 patients performing distal weakness exceeding proximal weakness . One family with autosomal dominant inheritance of 11 patients had a later age of onset than the sporadic ones and manifested bilateral ptosis , bilateral lower limbs weakness , especially in distal muscle.Muscle biopsies showed pronouncedly increased amount of fibers with centrally placed nuclei with predominant type Ⅰfibers and a clear perinuclear halo surrounding the centrally placed nuclei and an appearance of spoke of a wheel in some fibers.Conclusions This series of centronuclear myopathy patients manifest clinical heterogeneity.Muscle biopsies show features of centralized nuclei pronounced increase , type Ⅰfibers predominance , etc.These can provide evidences for the diagnosis of the disease.

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 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.

A Case of Centronuclear Myopathy

Centronuclear myopathy is a rare congenital myopathy, which is characterized by centrally located nuclei and hypotrophy or predominance of type 1 fibers in muscle pathology. It is classified into three forms according to the clinical features and inheritance pattern: the X-linked recessive, the autosomal recessive, and the autosomal dominant forms. We report a case of a patient with generalized muscle weakness, poor muscle bulk, and dysmorphic features who was diagnosed as centronuclear myopathy.

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.

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.