Abstract:
Facioscapulohumeral muscular dystrophy (FSHD)-the worldwide third most common inherited muscular dystrophy caused by the heterozygous contraction of a 3.3 kb tandem repeat (D4Z4) on a chromosome with a 4q35 haplotype-is a progressive genetic myopathy with variable onset of symptoms, distribution of muscle weakness, and clinical severity. While much is known about the clinical course of adult FSHD, data on the early-onset infantile phenotype, especially on the progression of the disease, are relatively scarce. Contrary to the classical form, patients with infantile FSHD more often have a rapid decline in muscle wasting and systemic features with multiple extramuscular involvements. A rough correlation between the phenotypic severity of FSHD and the D4Z4 repeat size has been reported, and the majority of patients with infantile FSHD obtain a very short D4Z4 repeat length (one to three copies, EcoRI size 10-14 kb), in contrast to the classical, slowly progressive, form of FSHD (15-38 kb). With the increasing identifications of case reports and the advance in genetic diagnostics, recent studies have suggested that the infantile variant of FSHD is not a genetically separate entity but a part of the FSHD spectrum. Nevertheless, many questions about the clinical phenotype and natural history of infantile FSHD remain unanswered, limiting evidence-based clinical management. In this review, we summarize the updated research to gain insight into the clinical spectrum of infantile FSHD and raise views to improve recognition and understanding of its underlying pathomechanism, and further, to advance novel treatments and standard care methods.
摘要:
面肩肱肌营养不良症(FSHD)-由具有4q35单倍型的染色体上3.3kb串联重复序列(D4Z4)的杂合子收缩引起的全球第三大最常见的遗传性肌营养不良症,是一种进行性遗传性肌病,具有不同的症状发作,肌肉无力的分布,和临床严重程度。虽然对成人FSHD的临床过程了解很多,早发性婴儿表型的数据,特别是关于疾病的进展,相对稀缺。与古典形式相反,婴儿FSHD患者更经常出现肌肉萎缩和全身特征快速下降,并伴有多次肌外受累。据报道,FSHD的表型严重程度与D4Z4重复大小之间存在粗略的相关性,大多数婴儿FSHD患者获得了非常短的D4Z4重复长度(一到三个拷贝,EcoRI大小10-14kb),与古典相比,慢慢进步,FSHD的形式(15-38kb)。随着病例报告的日益增多和基因诊断的进步,最近的研究表明,FSHD的婴儿变体不是遗传上独立的实体,而是FSHD谱的一部分。然而,关于婴儿FSHD的临床表型和自然史的许多问题仍然没有答案,限制循证临床管理。在这次审查中,我们总结了最新的研究,以深入了解婴儿FSHD的临床频谱,并提出意见,以提高对其潜在病理机制的认识和理解,进一步,推进新的治疗方法和标准的护理方法。