Abstract
X-linked myotubular myopathy (X-МTM) is a serious and potentially fatal myopathy resulting from a mutation in the myotubularin (MTM1) gene. The primary clinical features include widespread muscle weakness, early-onset hypotension, and respiratory failure, along with various associated conditions that frequently lead to mortality. The authors present a clinical case involving a 3.5-year-old boy diagnosed with X-linked myotubular myopathy. This patient was monitored from the age of 11 months, with the diagnosis confirmed at 1.4 years through whole-genome sequencing. A novel nonsense mutation in exon 7 of the MTM1 gene was discovered, which is responsible for the onset of X-linked myotubular myopathy. The mutation in the myotubularin (MTM1) gene disrupts the normal development and functioning of myocytes, resulting in a distinct triad of symptoms: widespread muscle weakness, neonatal hypotonia, and respiratory failure. Furthermore, several additional features typical of X-linked myotubular myopathy have been identified: physical characteristics (such as dolichocephaly, arachnodactyly, elongated limbs, and tall stature), cryptorchidism, joint contractures, dysphagia accompanied by weakness in the swallowing muscles, psychomotor retardation, peliosis hepatis, and progressive ophthalmoplegia. X-linked myotubular myopathy can result in severe, life-threatening complications, highlighting the critical need for early diagnosis and intervention. Given the infrequency of this condition, the potential for de novo mutations in the gene, and the extensive differential diagnosis that includes both myopathies and bronchopulmonary disorders, it is vital to gather clinical data on X-linked myotubular myopathy. Consequently, it is imperative to engage clinicians and establish protocols for the early detection of myopathy within the first year of life to reduce the risks associated with delayed diagnosis and management errors.