1/44. Congenital fiber type disproportion: severe form with marked improvement. A 30-month-old male exhibited marked hypotonia at birth accompanied by respiratory distress necessitating ventilator support. He subsequently demonstrated marked improvement in muscle power. He became independent of the respirator at 21 days of age and was able to sit without support at 11 months and walked alone at 24 months. Histopathologic analysis of the quadriceps femoris muscle confirmed the diagnosis of congenital fiber type of disproportion at 11 months of age. No other studies have described a patient with a severe neonatal form of congenital fiber type of disproportion who demonstrated such clear improvement. physicians should be aware of this possibility when they interact with such patients and their families. ( info) |
2/44. A clinical and genetic study of a manifesting heterozygote with X-linked myotubular myopathy. X-linked myotubular myopathy (XLMTM) characteristically causes severe or fatal muscle weakness in male infants. Mutations in the gene MTM1, encoding the protein myotubularin, can be identified in most families. Prior to this report, XLMTM was thought not to cause symptomatic manifestations in female carriers. We describe an adult female from a large family with typical XLMTM. The patient had progressive disabling muscle weakness of later onset and lesser severity than that observed in affected males. The distribution of weakness resembled typical XLMTM with facial weakness, marked limb-girdle weakness, respiratory muscle involvement and dysphagia. Analysis of the MTM1 gene identified a heterozygous missense mutation (G378R) within the highly conserved tyrosine phosphatase site of myotubularin. We did not identify significantly skewed X-inactivation. We conclude that XLMTM is capable of causing significant disability in heterozygotes. ( info) |
3/44. X-linked myotubular myopathy--a long-term follow-up study. X-Linked myotubular myopathy is a well delineated congenital myopathy, with a high neonatal and early childhood mortality. Only a single gene, mapping to Xq28 has been implicated and has recently been characterized. Phenotypic variability, both inter- and intrafamilial, has been recorded. Its severest expression is a uniform disease with polyhydramnios due to prenatal (neuromuscular) swallowing disorder, and partial inability to expand the lungs postnatally leading to early postnatal death in all. The mildest expression appears to be represented by the first family reported in the literature in which intrafamilial phenotypic variability was marked. There was neonatal asphyxia, but recovery took place in most affected patients and very mild expression permitting normal life into adulthood has been found in two patients. A long-term follow-up is given on both these families. Results emphasize the importance of the family history when trying to prognosticate in an individual case. ( info) |
4/44. Anaesthesia in myotubular (centronuclear) myopathy. A patient with a known history of myotubular myopathy presented for surgery for insertion of a tibial nail. Anasthesia was induced and maintained using an intravenous anasthetic technique. Neuromuscular function was assessed using mechanomyography, which showed a profound reduction in muscle contractility. In view of this, the use of muscle relaxants was avoided altogether. Nerve conduction was normal but electromyography showed small motor units, with generalised distribution, suggesting mild to moderately severe myopathy. The patient made a slow but uneventful recovery. ( info) |
5/44. Congenital fibre type disproportion a time-locked diagnosis: a clinical and morphological follow-up study. This is the first report that describes the clinical and histological findings in a patient suffering from pure congenital fibre type disproportion (CFTD), who had two biopsies with an interval of 16 years. Additionally, we compared the clinical signs and symptoms of the present case to those of 35 CFTD cases reviewed from the literature. From this we conclude that smallness of type I fibre diameter is not a characteristic feature during the course of pure CFTD. This suggests that CFTD is a time-locked diagnosis. ( info) |
6/44. Congenital fiber-type disproportion presenting antenatally with clubfoot and hydramnios. This is a case of congenital fiber-type disproportion that presented prenatally with bilateral clubfoot, hydramnios, and reduced fetal movements. Although prognosis is generally good for this condition, the neonate presenting at birth may have a more severe form of congenital fiber-type disproportion with a high rate of mortality. ( info) |
7/44. alternative splicing of exon 17 and a missense mutation in exon 20 of the insulin receptor gene in two brothers with a novel syndrome of insulin resistance (congenital fiber-type disproportion myopathy). The insulin receptor (IR) in two brothers with a rare syndrome of congenital muscle fiber type disproportion myopathy (CFTDM) associated with diabetes and severe insulin resistance was studied. By direct sequencing of Epstein-Barr virus-transformed lymphocytes both patients were found to be compound heterozygotes for mutations in the IR gene. The maternal allele was alternatively spliced in exon 17 due to a point mutation in the -1 donor splice site of the exon. The abnormal skipping of exon 17 shifts the amino acid reading frame and leads to a truncated IR, missing the entire tyrosine kinase domain. In the correct spliced variant, the point mutation is silent and results in a normally translated IR. The paternal allele carries a missense mutation in the tyrosine kinase domain. All three cDNA variants were present in the lymphocytes of the patients. Purified IR from 293 cells overexpressing either of the two mutated receptors lacked basal or stimulated IR beta-subunit autophosphorylation. A third brother who inherited both normal alleles has an normal muscle phenotype and insulin sensitivity, suggesting a direct linkage of these IR mutations with the CFTDM phenotype. ( info) |
8/44. temporomandibular joint involvement in a patient with centronuclear myopathy. We describe here the temporomandibular joint and masticatory muscle abnormalities disclosed by computed tomography and magnetic resonance imaging in a 25-year-old man with centronuclear myopathy (a congenital myopathy) who presented with marked limitation of jaw movements. We found an intense and general fatty replacement of the masticatory muscles, and magnetic resonance imaging signals indicated articular fibrosis. We conclude that in centronuclear myopathy, the presence of weakness and hypomotility of the masticatory muscles can induce chronic abnormalities of the temporomandibular joint. ( info) |
9/44. Diagnostic challenges in combined multiple sclerosis and centronuclear myopathy. The first case of combined centronuclear myopathy and multiple sclerosis is reported. The difficulties of diagnosing multiple sclerosis in patients with muscular disorders associated with the central nervous system involvement are discussed. ( info) |
10/44. siblings of Schwartz-Jampel syndrome with abnormal muscle computed tomographic findings. Schwartz-Jampel syndrome (SJS) is a disorder characterized by myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation. We present two boys of ages 4 and 8 years with SJS. Their clinical, electromyographic and histopathological findings were similar to those described, except for computed tomography (CT) images that revealed diffuse high attenuation in sternocleidomastoid muscles and low attenuation in the paraspinal, quadriceps, sartorius, soleus and gastrocnemius muscles. This is the first report describing abnormal muscle CT findings associated with SJS. Additional studies of muscle CT might help to improve understanding of the pathogenesis of SJS. ( info) |