Lohkamp Laura Nanna, von Au Katja, Goebel Hans-Hilmar, Kress Wolfram, Grieben Ulrike, Drossel Karin, Garbes Lutz, Wirth Brunhilde, Heppner Frank L, Stenzel Werner
1Department of Neuropathology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
J Child Neurol. 2014 Feb;29(2):254-9. doi: 10.1177/0883073813511858. Epub 2013 Dec 11.
Spinal muscular atrophy is an autosomal-recessive neuromuscular disorder, causing progressive proximal weakness and atrophy of the voluntary muscles. More than 96% of the spinal muscular atrophy patients show a homozygous absence of exons 7 and 8, or exon 7 only, in SMN1, the telomeric copy of the SMN gene. We report a young male patient with neurogenic symptoms and sparse muscle fiber atrophy, suggestive of a mild form of type III spinal muscular atrophy. He was found to be a carrier of intragenic mutations in both copies of the SMN gene, exhibiting a homozygous duplication of exons 7 and 8 in SMN1 and a homozygous deletion of exon 8 as well as a heterozygous deletion of exon 7 in SMN2. However, an intact full-length SMN1 complementary deoxyribonucleic acid was identified, and SMN protein levels in a muscle specimen were identical to that of a healthy control, formally excluding the diagnosis of spinal muscular atrophy III.
脊髓性肌萎缩症是一种常染色体隐性神经肌肉疾病，会导致进行性近端肌无力和随意肌萎缩。超过96%的脊髓性肌萎缩症患者在SMN基因的端粒拷贝SMN1中，显示外显子7和8纯合缺失，或仅外显子7缺失。我们报告了一名年轻男性患者，有神经源性症状和稀疏的肌纤维萎缩，提示为轻度III型脊髓性肌萎缩症。发现他是SMN基因两个拷贝中基因内突变的携带者，在SMN1中外显子7和8纯合重复，在SMN2中外显子8纯合缺失以及外显子7杂合缺失。然而，鉴定出完整的全长SMN1互补脱氧核糖核酸，并且肌肉标本中的SMN蛋白水平与健康对照相同，从而正式排除了III型脊髓性肌萎缩症的诊断。
