Chinese Medical Sciences Journal ›› 2021, Vol. 36 ›› Issue (4): 265-278.doi: 10.24920/003883

• Original Articles • Previous Articles     Next Articles

BAG3-Related Myofibrillar Myopathy Presenting as Hypercapnia: A Case Report and Literature Review

Yan Xu1, Shixuan Liu2, Wenbing Xu1, Jinmei Luo1, Jingwen Niu3, Zhi Liu3, Jinming Gao1, Jinglan Wang1, Yi Dai3, *(), Mengzhao Wang1, *()   

  1. 1Department of Respiratory and Critical Care Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
    2Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
    3Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
  • Received:2021-01-25 Published:2021-12-31 Online:2021-10-09
  • Contact: Yi Dai,Mengzhao Wang E-mail:pumchdy@pumch.cn;mengzhaowang@sina.com
In this report, the authors describe a sporadic case of a 14-year-old Chinese girl with a de novo p.Pro209Leu mutation in BAG3 who presented with skeletomuscular and peripheral nerve dysfunction in childhood and gradually appearing symptoms of hypercapnia that required assisted ventilation, suggesting that BAG3-associated MFM should be considered as a rare differential diagnosis of hypercapnia.

Objective BAG3-related myopathy is a rare condition so far reported in twenty patients worldwide. The purpose of this study was to draw attention to this rare disease and to the fact that BAG3-related myopathy should be considered as a rare differential diagnosis of hypercapnia.
Methods We report a sporadic case of a 14-year-old Chinese girl with a de novo p.Pro209Leu mutation in BAG3 and reviewed the literatures for reported cases related to this mutation.
Results We described a 14-year-old Chinese girl who presented with gradually appearing symptoms of hypercapnia that required assisted ventilation. The muscle biopsy and the blood whole-exome sequencing results confirmed the diagnosis of myofibrillar myopathy with a de novo p.Pro209Leu mutation in BAG3. Totally twenty-one patients from twenty families with a confirmed diagnosis of BAG3-related myopathy were reported to date, including this patient and literature review. The male to female ratio was 11:10 and most showed initial symptoms in the first decade of life. Most patients presented toe/clumsy walking or running as the onset symptom, followed by muscle weakness or atrophy. Creatine kinase levels were elevated in fourteen patients and were normal in three. Eighteen patients developed respiratory insufficiency during the disease course and thirteen (one could not tolerate non-invasive assisted ventilation) required non-invasive assisted ventilation for treatment. Except for one not reported, heart involvement was found in seventeen patients during the disease course and seven underwent heart transplantation. Z-disk streaming and aggregation could be observed in most of the patients’ muscle histology. In the long-term follow-up, five patients died of cardiac or respiratory failure.
Conclusion BAG3-associated myopathy is a rare type of myofibrillar myopathy. It should be considered as a rare differential diagnosis of hypercapnia.

Key words: myofibrillar myopathy, BAG3, respiratory insufficiency, hypercapnia

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