Myoadenylate deaminase deficiency: inherited and acquired forms |
| |
| Authors: | W N Fishbein |
| |
| Affiliation: | 1. Department of Neurology, Huashan Hospital Fudan University, Shanghai 200040, China;2. Department of Pathology, Huashan Hospital Fudan University, Shanghai 200040, China;3. Department of Neurology, Nanjing Drum Tower hospital, the affiliated hospital of Nanjing University Medical School, Jiangsu 210008, China;4. Department of Neurology, Jing''an District Center Hospital of Shanghai, Shanghai 200040, China;5. Department of Pathology, Jing''an District Center Hospital of Shanghai, Shanghai 200040, China;6. Department of Radiology, Jing''an District Center Hospital of Shanghai, Shanghai 200040, China;7. Folkhälsan Research Center, Medicum, University of Helsinki, Helsinki, Finland;8. Neuromuscular Research Center, University of Tampere and Tampere University Hospital, Tampere, Finland;1. Division of Neurology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand;2. Division of Hematology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand;3. Department of Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok Thailand;4. Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo Japan;1. Department of Paediatric Neurology, University Children''s Hospital Zürich, Zürich, Switzerland;2. Dubowitz Neuromuscular Centre, Institute of Child Health, Great Ormond Street Hospital, London, United Kingdom;3. Department of Neuropathology, University Hospital Zürich, Zürich, Switzerland;4. Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;1. Department of Laboratory Medicine, Gyeongsang National University Hospital, Gyeongsangnam-do, South Korea;2. Department of Laboratory Medicine, College of Medicine, Chosun University Medical School, Gwang-Ju, South Korea;3. Green Cross Reference Laboratory, Yong-In, Gyeonggi-do, South Korea;4. Department of Laboratory Medicine, National Medical Center, Seoul, South Korea;5. Department of Laboratory Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea;6. Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea;7. Biomedical Research Institute, Seoul National University Hospital, Seoul, South Korea |
| |
| Abstract: | Myoadenylate deaminase deficiency, the most common of the known enzyme deficits of muscle, appears to occur in two forms. The primary type seems to be inherited as a complete gene block in an autosomal recessive pattern. Although occasionally diagnosed in infancy, when muscle biopsy is performed on a hypotonic but normoreflexic child, the deficiency is usually not symptomatic until adult or middle age, when muscle cramping and exercise intolerance develop. The skeletal muscle isozyme is immunologically, and presumably genetically, unique, and these patients have normal levels of adenylate deaminase in their other cells and tissues. A presumptive diagnosis can usually be made by an ischemic forearm exercise test, which shows a negligible increase in blood ammonia, despite a normal rise in lactate. Despite the absence of more than 99% of normal adenylate deaminase activity, the muscle biopsy shows no anatomic pathology, and other enzymes are at normal levels. These patients do not suffer progressive disease, and should be reassured, and encouraged to maintain physical activity. The heterozygous state is probably asymptomatic, except, perhaps, on extreme exercise, but may be associated with an increased incidence of malignant hyperthermia susceptibility. Since the gene defect is not rare, it is not surprising that some cases of the deficiency will be coincidentally associated with other neuromuscular disease. However, there is also a secondary form of myoadenylate deaminase deficiency, consequent to muscle damage from other disease. In this form, the residual activity is higher (1-10% of normal), may present rare foci of positive stain in the section, and reacts normally with antibody to the muscle isozyme. Other muscle enzymes are also depleted, although not as severely, and the prognosis in such cases is dictated by the primary disease. Since the heterozygous state is common, these patients might have been carriers, whose adenylate deaminase levels have been lowered for the deficient category by the advent of other neuromuscular disease. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
