X-linked spinal and bulbar muscular atrophy (Kennedy’s disease): the first case described in the Brazilian Amazon

ABSTRACT The X-linked spinal and bulbar muscular atrophy (Kennedy’s disease) is a rare X-linked, recessive, lower motor neuron disease, characterized by weakness, atrophy, and fasciculations of the appendicular and bulbar muscle. The disease is caused by an expansion of the CAG repetition in the androgen receptor gene. Patients with Kennedy’s disease have more than 39 CAG repetitions. We report a case of 57-year-old man, resident of Monte Dourado (PA, Brazil) who complained of brachiocrural paresis evolving for 3 years along with fasciculations and tremors of extremities. In addition, he also developed dysarthria, dysphagia, and sexual dysfunction. The patient clinical picture included gait impairment, global hyporeflexia, proximal muscle atrophy of upper limbs, deviation of the uvula to right during phonation and tongue atrophy with fasciculations. The patient reported that about 30 years ago he had undergone gynecomastia surgery. His electroneuromyography suggested spinal muscular atrophy, and nuclear magnetic resonance imaging showed tapering of the cervical and thoracic spinal cord. Patient’s creatine kinase level was elevated. In view of the findings, an exam was requested to investigate Kennedy’s disease. The exam identified 46 CAG repetitions in the androgen receptor gene, which confirmed the diagnostic suspicion. This was the first case of Kennedy’s disease diagnosed and described in the Brazilian Amazon. To our knowledge only other four papers were published on this disease in Brazilian patients. A brief review is also provided on etiopathogenic, clinical and diagnostic aspects.

摘要
X连锁脊髓延髓肌萎缩症（X-linked spinal and bulbar muscular atrophy，又称Kennedy病）是一种罕见的X连锁隐性遗传性下运动神经元疾病，以肢体及延髓肌群无力、萎缩和肌束震颤为典型特征。该病的致病机制为雄激素受体基因内的CAG重复序列扩增。Kennedy病患者的该基因CAG重复次数通常超过39次。
本文报告1例居住于巴西帕拉州蒙特杜拉多的57岁男性患者，该患者主诉四肢轻瘫渐进性加重3年，伴肢体肌束震颤与震颤。此外，患者还出现构音障碍、吞咽困难及性功能障碍。
患者的临床表现包括步态异常、全身性反射减退、上肢近端肌肉萎缩，发音时悬雍垂右偏，舌肌萎缩伴肌束震颤。患者自述约30年前曾接受男性乳房发育症手术。
肌电图（electroneuromyography）检查提示脊髓性肌萎缩，核磁共振成像显示颈段及胸段脊髓变细。患者血清肌酸激酶水平升高。结合上述检查结果，临床开具了针对Kennedy病的筛查检测，结果显示其雄激素受体基因中存在46个CAG重复序列，证实了临床的诊断推测。
该病例为巴西亚马逊地区首例确诊并报道的Kennedy病病例。据我们所知，目前仅另有4篇针对巴西籍患者该病的研究论文发表。本文同时简要综述了该病的病因发病机制、临床表现及诊断相关要点。