Floppy Infant Caused by MTM1 Mutation: A First Genetically-Confirmed X-Linked Myotubular Myopathy Patient in Thailand
Teerin Liewluck MD*,***,*****, Natte Raksadawan MD**, Chanin Limwongse MD***,****, Ichizo Nishino MD, PhD*****, Tumtip Sangruchi MD*,***
Affiliation : * Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University ** Neuroscience Center, Bangkok Hospital *** Neurogenetic Network, Faculty of Medicine Siriraj Hospital, Mahidol University **** Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University ***** Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
Floppy infant syndrome (FIS) refers to a condition wherein an infant manifests generalized hypoto- nia since birth or in early life. It is heterogeneous and can be caused by various central nervous system disorders, neuromuscular diseases and genetic disorders. X-linked myotubular myopathy (XMTM) is a pro- gressive congenital myopathy morphologically characterized by the presence of centrally placed nuclei in numerous muscle fibers without any other particular pathological abnormalities. Patients are frequently born with floppiness and respiratory distress. The vast majority of patients carry a truncating or missense mutation in MTM1. The authors report here a full term male baby with clinicopathological features of XMTM. The diagnosis is validated by the finding of a c.141-144delAGAA mutation of MTM1. To the best of the authors’ knowledge, the present case is the first genetically confirmed XMTM in Thailand. A brief review of various neuromuscular disorders causing floppy infant syndrome is also included.
Keywords : X-linked myotubular myopathy, Centronuclear myopathy, Congenital myopathy, Floppy infant, MTM1, Myotubularin, Muscle biopsy
