Case reportCentronuclear myopathy and cardiomyopathy requiring heart transplant
Introduction
Centronuclear myopathy (CNM) is a congenital myopathy, first described by Spiro et al. [1] in 1966. It is clinically characterized by generalized hypotonia, ptosis, ophthalmoplegia, and facial and limb weakness [2]. CNM has great clinical variability, ranging from a severe, fatal disorder (the neonatal X-linked form) to mild weakness with normal life expectancy (the autosomal recessive form). Classification is based on the age of onset, mode of inheritance, severity of involvement and rapidity of progress [3]. Three major patterns of inheritance have been described: the X-linked recessive form, called by some authors myotubular myopathy is linked to the Xq28 gene; the autosomal recessive form with childhood onset; and the autosomal dominant form, which has a milder course with adult onset [3], [4], [5], [6].
Diagnosis of the disease is based on clinical suspicion and the results of appropriate muscle histopathological and electron microscopic studies, and exclusion of other causes of centrally nucleated muscle fibers [3], [5]. CNM is suspected if the percentage of central nuclei in the muscle biopsy samples is increased (normal range ≤3%). This suspicion is supported by clinical evidence of facial and limb weakness and exclusion of other causes of muscular disorders associated with central nuclei [6].
The pathological features of CNM are an increased number of centrally nucleated muscle fibers, variation in the diameter of the muscle fibers, type I fiber predominance or atrophy, and a central area of the muscle cell devoid of activity on reaction with adenosinetriphosphatase (ATPase) [6], [7].
We report a case of CNM in a young girl with a rare presentation of severe dilated cardiomyopathy that necessitated heart transplantation. To the best of our knowledge, this is the first reported patient with CNM to successfully undergo heart transplantation.
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Case report
A 3.5-year-old girl, who presented with early-onset dilated cardiomyopathy, biventricular hypertrophy and CNM, was born at term; her birth weight was 3.4 kg. The pregnancy was uncomplicated; fetal movements were perceived to be normal; the postnatal period was uneventful; and her developmental history was normal.
At age 30 months, the patient presented with fever, cough, shortness of breath and lethargy. Subsequently, she developed acute congestive heart failure. After being diagnosed with
Discussion
Although cardiomyopathy is commonly associated with other childhood myopathies, our patient is the youngest reported with CNM presenting with heart failure caused by cardiomyopathy. CNM is rarely associated with cardiomyopathy: only three reports [2], [7], [9] have indicated this association. Almost all reported patients with CNM and cardiac manifestations die because of congestive heart failure. Our patient was the first patient with CNM and congestive heart failure to successfully undergo
Acknowledgements
This manuscript was prepared with the assistance of Editorial Services, The Hospital for Sick Children, Toronto, Canada.
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