A unique case of reducing body myopathy

Abstract

The clinical, electromyographic, and histologic characteristics of a 17-year-old girl with reducing body myopathy are described. She is, to our knowledge, the oldest reported case and the only patient described with severe mitral valve prolapse and scoliosis. Electromyography demonstrated spontaneous positive sharp waves and fibrillation potentials with many low-amplitude, short, polyphasic motor unit potentials. The right deltoid muscle was characterized by focal areas with large fibers associated with increased endomysial connective tissue and "split" fibers. Purple-gray sarcoplasmic masses stained with trichrome were PAS-negative, appeared as "empty" spaces with both ATPase and NADH-TR, and stained darkly with menadione NBT. The features described expand the clinical presentation of this myopathy, and may lead to a better understanding of its etiology.

Reducing Body Myopathy with Cytoplasmic Bodies and Rigid Spine Syndrome: A Mixed Congenital Myopathy

“…Decreased mobility of limb joints [7,29] including a rigid spine (our patient) may occur. Previously encountered patients only had sporadic reducing body myopathy whereas our patients neuromuscular disorder with reducing bodies suggested a familial setting, although reducing bodies as components of muscle fibre inclusions could not be retrospectively identified in archival light microscopic muscle tissue sections of his affected grandmother and were not present in the mothers biopsied muscle.…”

“…Reducing body myopathy is a rare disorder with only 16 patients reported, including this one ( Table 2). It may affect children [3,7], adolescents [29], and even adults [12,22]. It may run a rapidly fatal course [3], a protracted, but nevertheless fatal course [7], a protracted course marked by considerable respiratory problems [29], but also a benign course [12,22,30].…”

“…It may affect children [3,7], adolescents [29], and even adults [12,22]. It may run a rapidly fatal course [3], a protracted, but nevertheless fatal course [7], a protracted course marked by considerable respiratory problems [29], but also a benign course [12,22,30]. Others [23] distinguish three clinical types: a severe infantile type [3,23], a congenital, rather benign type [4,29], and a late-onset form [2,12,21].…”

“…Likewise, reducing body myopathy has been recognized repeatedly as a separate neuromuscular entity, sometimes occurring as a malignant condition in childhood [3,7], but sometimes as a benign form both in children [30,37] and in adulthood [21,22]. While detailed descriptions of muscle specimens in cytoplasmic body myopathy [27] did not mention additional reducing bodies, cytoplasmic bodies were occasionally mentioned in reducing body myopathy [2,3,21,37], but not in other instances of reducing body myopathy [4,29,30]. The not infrequent encounter of a few cytoplasmic bodies in a variety of neuromuscular conditions, not considered as congenital cytoplasmic body myopathy, renders the additional presence of a few cytoplasmic bodies in other patients muscle specimens afflicted with reducing body myopathy insignificant, particularly as in one instance [37] the cytoplasmic bodies were only recorded in a single myofibre which did not contain reducing bodies.…”

Proteomic identification of FHL1 as the protein mutated in human reducing body myopathy

“…Clinical presentations of RBM have ranged from early onset fatal to childhood onset to adult onset cases (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). It is noteworthy that the most severe cases frequently have included girls (13).…”