"Emergency medicine" №2(97), 2019

Background. Centronuclear myopathies (CNMs) are a group of clinically and genetically heterogeneous muscle disorders [1]. Myotubular myopathy, an X-linked form of CNM is characterized by neonatal hypotonia and inability to maintain unassisted respiration. The MTM1 gene, responsible for this disease, encodes myotubularin — a lipidic phosphatase involved in vesicle trafficking regulation and maturation [2]. Case report and discussion. We report a 7-month old male infant who has required mechanical ventilation since birth due to suspected neuromyopathy. Congenital adrenal hyperplasia, Pompe disease (type II glycogenosis), Prader — Willi syndrome, and SMA were excluded. Further genetic testing revealed a hemizygous variant (c. 64–2A > G) in MTM1. This variant is predicted to abolish the intron 2 splice donor site of MTM1 and has been reported in a male infant with severe X-linked myotubular myopathy [3]. Our patient’s mother and maternal grandmother were found to be heterozygous carriers of the c. 64–2A > G variant. Two variants of uncertain significance were detected in this patient’s MYH7 gene. MYH7 encodes the cardiac-specific beta heavy chain myosin protein and is a cause of autosomal dominant dilated cardiomyopathy and distal myopathy. One variant (p.Leu881Met) was inherited from the father and the other (p.Arg1749Gly) was inherited from the mother. The paternally inheri-ted variant is found in a region of the MYH7 protein where a significant number of previously reported MYH7 missense mutations are found [4]. Both MYH7 variants are absent from the ExAC public database. Thus, the genetic testing allowed us to diagnose the combined genetic pathology: myotubular myopathy and possibly dilated cardiomyopathy. This pathology causes the respiratory failure and the need of permanent respiratory support in a patient. Conclusions. The case report demonstrates importance of: 1) genetic screening in a population, especially in genetics-compromised parents, for family planning and timely detection of hereditary diseases during pregnancy; 2) early genetic testing to confirm the diagnosis of a sick child; 3) development of palliative and hospice medicine with the possibility of providing ventilation support at home by parents (guardians).