Brain Advance Access originally published online on April 27, 2005
Brain 2005 128(7):1716-1727; doi:10.1093/brain/awh511
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Autosomal dominant congenital fibre type disproportion: a clinicopathological and imaging study of a large family
1 Department of Pathology and Neuropathology, Hospital do Meixoeiro, Departments of 2 Neurophysiology and 3 Radiology, Complexo Hospitalario Xeral-Cíes, Vigo, 4 Fundación Pública Galega de Medicina Xenómica, Santiago de Compostela, 5 Neurology Unit, Complexo Hospitalario Arquitecto Marcide, Ferrol, 6 Department of Neuropathology, Hospital 12 Octubre, Madrid and 7 Department of Neurology, Complexo Hospitalario de Pontevedra, Pontevedra, Spain
Correspondence to: Dr Carmen Navarro, Department of Pathology and Neuropathology, Hospital do Meixoeiro, Vigo 36 200, Spain E-mail: carmen.navarro.fernandez.balbuena{at}sergas.es
Congenital fibre type disproportion (CFTD) is considered a non-progressive or slowly progressive muscle disease with relative smallness of type 1 fibres on pathological examination. Although generally benign, CFTD has a variable natural course and severe progression has been observed in some patients. The pathogenesis of the disorder is unknown and many authors consider CFTD a syndrome with multiple aetiologies rather than a separate clinical entity. A positive family history has been reported in about 40% of cases, but the inheritance pattern is not clear. Both autosomal recessive and dominant modes of inheritance have been suggested. The present paper describes a large, multigenerational kindred that has an inherited myopathy fulfilling the histological criteria of CFTD, with autosomal dominant transmission and high penetrance. The clinical picture, remarkably similar in all affected family members, started in early infancy with mild limb muscle weakness. There was slow progression of symptoms into adulthood, with moderate to severe, mainly proximal, muscle weakness without loss of ambulation. Muscle biopsy from two affected individuals demonstrated predominance of small type 1 muscle fibres without other significant findings. Nerve conduction studies were normal and needle electromyography showed a myopathic pattern. MRI examination performed on three patients from successive generations showed involvement of proximal limb and paraspinal muscles. The clinical and pathological homogeneity in the present family, together with the lack of additional histological abnormalities after decades of disease progression in two affected individuals, supports this being a distinct myopathy with fibre type disproportion. Whether the disease in this family can be regarded as a form of the congenital myopathy known as CFTD or rather a unique condition sharing histological features with CFTD needs further investigation. This is, to our knowledge, the largest kindred with muscle fibre type disproportion reported to date. Our data confirm autosomal dominant inheritance, and this is the first MRI document of this disorder.
Key Words: congenital fibre type disproportion; congenital myopathy; muscle MRI; autosomal dominant
Abbreviations: CFTD = congenital fibre type disproportion; DTR = deep tendon reflex
Received July 30, 2004. Revised February 14, 2005. Accepted March 17, 2005.