Department of Neurology, Hope Center for Neurological Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA.
Ann Neurol. 2012 Mar;71(3):407-16. doi: 10.1002/ana.22683. Epub 2012 Feb 14.
To identify the causative gene in an autosomal dominant limb-girdle muscular dystrophy (LGMD) with skeletal muscle vacuoles.
Exome sequencing was used to identify candidate mutations in the studied pedigree. Genome-wide linkage was then used to narrow the list of candidates to a single disease-associated mutation. Additional pedigrees with dominant or sporadic myopathy were screened for mutations in the same gene (DNAJB6) using exome sequencing. Skeletal muscle from affected patients was evaluated with histochemistry and immunohistochemical stains for dystrophy-related proteins, SMI-31, TDP43, and DNAJB6.
Exome analysis in 3 affected individuals from a family with dominant LGMD and vacuolar pathology identified novel candidate mutations in 22 genes. Linkage analysis excluded all variants except a Phe93Leu mutation in the G/F domain of the DNAJB6 gene, which resides within the LGMD locus at 7q36. Analysis of exome sequencing data from other pedigrees with dominant myopathy identified a second G/F domain mutation (Pro96Arg) in DNAJB6. Affected muscle showed mild dystrophic changes, vacuoles, and abnormal aggregation of proteins, including TDP-43 and DNAJB6 itself.
Mutations within the G/F domain of DNAJB6 are a novel cause of dominantly-inherited myopathy. DNAJB6 is a member of the HSP40/DNAJ family of molecular co-chaperones tasked with protecting client proteins from irreversible aggregation during protein synthesis or during times of cellular stress. The abnormal accumulation of several proteins in patient muscle, including DNAJB6 itself, suggest that DNAJB6 function is compromised by the identified G/F domain mutations.
鉴定伴有骨骼肌空泡的常染色体显性肢带型肌营养不良症（LGMD）的致病基因。
利用外显子组测序鉴定研究家系中的候选突变。然后进行全基因组连锁分析，将候选突变缩小到与单一疾病相关的突变。使用外显子组测序，对具有显性或散发性肌病的其他家系进行相同基因（DNAJB6）的突变筛查。用组织化学和免疫组织化学染色评估受影响患者的骨骼肌，以检测与肌营养不良相关的蛋白，如 SMI-31、TDP43 和 DNAJB6。
对一个具有显性 LGMD 和空泡病理的家系的 3 名受影响个体进行外显子组分析，鉴定出 22 个基因中的新候选突变。连锁分析排除了所有变体，除了 DNAJB6 基因 G/F 结构域中的 Phe93Leu 突变外，该突变位于 7q36 的 LGMD 基因座内。对其他具有显性肌病的家系的外显子组测序数据进行分析，发现 DNAJB6 中的第二个 G/F 结构域突变（Pro96Arg）。受影响的肌肉显示出轻微的肌营养不良变化、空泡和异常聚集的蛋白，包括 TDP-43 和 DNAJB6 本身。
DNAJB6 的 G/F 结构域内的突变是一种新的显性遗传性肌病的原因。DNAJB6 是 HSP40/DNAJ 家族的成员之一，该家族的分子伴侣共同参与保护客户蛋白在蛋白质合成过程中或细胞应激时免受不可逆聚集。在患者肌肉中异常积累了几种蛋白，包括 DNAJB6 本身，这表明鉴定的 G/F 结构域突变会影响 DNAJB6 的功能。
