Vainzof M, Takata R I, Passos-Bueno M R, Pavanello R C, Zatz M
Departamento de Biologia, Universidade de São Paulo, Brazil.
Hum Mol Genet. 1993 Jan;2(1):39-42. doi: 10.1093/hmg/2.1.39.
The severe Duchenne muscular dystrophy (DMD) and the more benign Becker type (BMD) are allelic conditions, controlled by a defective gene at Xp21, caused by the absence (DMD) or a defect in quantity or quality (BMD) of the protein dystrophin. It has been suggested that the C-terminus domain of dystrophin is fundamental to ensure the proper protein sub-cellular localization and function. We wish to report our dystrophin findings in 4 among 142 DMD patients studied for DNA deletions and dystrophin analysis. Although they have a severe clinical course, a positive dystrophin immunofluorescence pattern was seen using C-terminal antibody, and a dystrophin band of reduced molecular weight (corresponding to their DNA deletions), but which maintained the C-terminus was seen through Western blot (WB). Based on these findings, we suggest that in order to partially maintain its function, resulting in a milder phenotype, dystrophin may carry large internal deletions but in addition to the C-terminus, the region encompassing both the N-terminus and the proximal region of the rod domain cannot be absent. Therefore, the prognosis of a Becker phenotype in a young patient should be done with caution if based only on the presence or not of dystrophin.
严重的杜兴氏肌营养不良症（DMD）和较为良性的贝克型（BMD）是等位基因疾病，由Xp21上的缺陷基因控制，是由于抗肌萎缩蛋白缺失（DMD）或其数量或质量存在缺陷（BMD）所致。有人提出，抗肌萎缩蛋白的C末端结构域对于确保蛋白质在亚细胞中的正确定位和功能至关重要。我们希望报告在142例接受DNA缺失和抗肌萎缩蛋白分析的DMD患者中的4例患者的抗肌萎缩蛋白研究结果。尽管他们有严重的临床病程，但使用C末端抗体可观察到阳性的抗肌萎缩蛋白免疫荧光模式，并且通过蛋白质印迹法（WB）可观察到分子量降低的抗肌萎缩蛋白条带（与他们的DNA缺失相对应），但该条带保留了C末端。基于这些发现，我们认为，为了部分维持其功能，从而产生较轻的表型，抗肌萎缩蛋白可能携带大段内部缺失，但除了C末端外，包含N末端和杆状结构域近端区域的区域不能缺失。因此，如果仅基于抗肌萎缩蛋白的有无来判断年轻患者的贝克型表型的预后，应谨慎行事。
