层粘连蛋白α2型肌营养不良症：22例患者的基因型/表型研究

Laminin alpha2 muscular dystrophy: genotype/phenotype studies of 22 patients.

作者信息

Pegoraro E, Marks H, Garcia C A, Crawford T, Mancias P, Connolly A M, Fanin M, Martinello F, Trevisan C P, Angelini C, Stella A, Scavina M, Munk R L, Servidei S, Bönnemann C C, Bertorini T, Acsadi G, Thompson C E, Gagnon D, Hoganson G, Carver V, Zimmerman R A, Hoffman E P

机构信息

Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, PA 15261, USA.

出版信息

Neurology. 1998 Jul;51(1):101-10. doi: 10.1212/wnl.51.1.101.

DOI:10.1212/wnl.51.1.101

PMID:9674786

Abstract

OBJECTIVE

To determine the number of primary laminin alpha2 gene mutations and to conduct genotype/phenotype correlation in a cohort of laminin alpha2-deficient congenital muscular dystrophy patients.

BACKGROUND

Congenital muscular dystrophies (CMD) are a heterogeneous group of muscle disorders characterized by early onset muscular dystrophy and a variable involvement of the CNS. Laminin alpha2 deficiency has been reported in about 40 to 50% of cases of the occidental, classic type of CMD. Laminin alpha2 is a muscle specific isoform of laminin localized to the basal lamina of muscle fibers, where it is thought to interact with myofiber membrane receptor, such as integrins, and possibly dystrophin-associated glycoproteins.

METHODS

Seventy-five CMD patients were tested for laminin alpha2 expression by immunofluorescence and immunoblot. The entire 10 kb laminin alpha2 coding sequence of 22 completely laminin alpha2-deficient patients was screened for causative mutations by reverse transcription (RT)-PCR/single strand conformational polymorphisms (SSCP) analysis and protein truncation test (PTT) analysis followed by automatic sequencing of patient cDNA. Clinical data from the laminin alpha2-deficient patients were collected.

RESULTS

Thirty laminin alpha2-negative patients were identified (40% of CMD patients tested) and 22 of them were screened for laminin alpha2 mutations. Clinical features of laminin alpha2-deficient patients were similar, with severe floppiness at birth, delay in achievement of motor milestones, and MRI findings of white matter changes with normal intelligence. Loss-of-function mutations were identified in 95% (21/22) of the patients studied. SSCP analysis detected laminin alpha2 gene mutations in about 50% of the mutant chromosomes; PTT successfully identified 75% of the mutations. A two base pair deletion mutation at position 2,096-2,097 bp was present in 23% of the patients analyzed.

CONCLUSIONS

Our data suggest that the large majority of laminin alpha2-deficient patients show laminin alpha2 gene mutations.

摘要

目的

确定原发性层粘连蛋白α2基因突变的数量，并在一组层粘连蛋白α2缺乏的先天性肌营养不良患者中进行基因型/表型相关性研究。

背景

先天性肌营养不良（CMD）是一组异质性肌肉疾病，其特征为早期发病的肌营养不良以及中枢神经系统的不同程度受累。在西方经典型CMD病例中，约40%至50%的病例报道存在层粘连蛋白α2缺乏。层粘连蛋白α2是层粘连蛋白的一种肌肉特异性异构体，定位于肌纤维的基膜，据认为它在那里与肌纤维膜受体（如整合素）以及可能的肌营养不良蛋白相关糖蛋白相互作用。

方法

通过免疫荧光和免疫印迹对75例CMD患者进行层粘连蛋白α2表达检测。对22例完全缺乏层粘连蛋白α2的患者的整个10 kb层粘连蛋白α2编码序列进行致病突变筛查，采用逆转录（RT）-聚合酶链反应/单链构象多态性（SSCP）分析和蛋白质截短试验（PTT）分析，随后对患者cDNA进行自动测序。收集层粘连蛋白α2缺乏患者的临床数据。

结果

共鉴定出30例层粘连蛋白α2阴性患者（占检测的CMD患者的40%），其中22例进行了层粘连蛋白α2突变筛查。层粘连蛋白α2缺乏患者的临床特征相似，出生时严重松软，运动发育里程碑延迟，MRI表现为白质改变且智力正常。在所研究的患者中，95%（21/22）鉴定出功能丧失突变。SSCP分析在约50%的突变染色体中检测到层粘连蛋白α2基因突变；PTT成功鉴定出75%的突变。在23%的分析患者中存在位于2096 - 2097 bp位置的两个碱基对缺失突变。