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Centronuclear myopathy (CNM) is a congenital myopathy characterized by chains of centrally located nuclei in a large number of muscle fibers. Clinically, an early-onset form was reported in several autosomal-recessive (AR) families and many sporadic patients, whereas a late-onset form was found in most autosomal-dominant (AD) families. The boundary between these two forms remains unclear, and the molecular basis of autosomal CNM is still unresolved. To better define the clinical and morphologic characteristics of autosomal CNM, the authors analyzed a series of 29 patients from 12 families. Two subgroups were identified in three AD families two families had a relatively late onset of disease and a slow progression of diffuse weakness, whereas the third family, who had a similar clinical course, also presented a unique diffuse muscle hypertrophy. Two presumed AR families and seven sporadic patients were analyzed together, and three subgroups were identified 1) an early-onset form with ophthalmoparesis; 2) an early-onset form without ophthalmoparesis; and 3) a late-onset form without ophthalmoparesis. Overall, 23 muscle biopsies were reviewed; a majority of patients had >20 central nuclei, fiber type 1 predominance, and a radial distribution of sarcoplasmic strands on oxidative stains. A marked endomysial fibrosis was observed in three sporadic patients with a relatively severe clinical course. The classification reported in this study will be useful for the diagnosis and the follow-up evaluation of patients with autosomal CNM and for the research into the molecular defects underlying the condition.

Respiratory syncytial virus (RSV) lower respiratory tract infections are considered to be a serious disease in centres such as the Sophia Children's Hospital (Rotterdam, the Netherlands), but as more benign infections in others such as the Geneva Children's Hospital (Switzerland). To assess the clinical severity of RSV infections at the two sites, 151 infants primarily admitted with a virologically confirmed RSV infection were studied prospectively (1994-5) and retrospectively (1993-4) (55 infants in Geneva and 96 in Rotterdam). Parameters of RSV morbidity which were more severe in Rotterdam during the two winter seasons were apnoea (1.8v 23.9%), the rate of admission to the intensive care unit (3.6 v 28.1%), mechanical ventilation (0 v 7.3%), and length of stay in hospital (6.8 v 9.1 days). In Geneva higher respiratory rates (59.2 v51.2), more wheezing (65.5 v 28.8%), and more retractions (81.8 v 63.3%) were recorded. Fewer infants younger than 4 months (54.9 v 68.7%), but more breast fed infants (94.1 v38.5%), were admitted in Geneva, although the morbidity parameters remained different after correction for these two variables in multivariate analyses. Thus unidentified local factors influence the pattern and severity of RSV infection and may affect the results of multicentre prophylactic and therapeutic studies.