X-Linked Myotubular Myopathy and Duchenne Muscular Dystrophy
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This male infant was born prematurely to a primigravida mother at 31 weeks gestation by cesarean delivery under general anesthesia because of placental abruption and antepartum hemorrhage. The pregnancy was uneventful and there was no history of polyhydramnios. The infant was floppy at birth and showed no respiratory effort but had a good heart rate. He was intubated and given surfactant with a provisional diagnosis of respiratory distress syndrome.

Despite minimal ventilation requirements, the infant continued to have poor respiratory effort and failed several attempts at extubation and trials of noninvasive ventilation. Direct laryngotracheal bronchoscopy did not reveal any airway abnormalities. The infant remained hypotonic with a paucity of limb movements. He had facial weakness and poor gag and suck reflexes. His deep tendon reflexes were difficult to elicit. He was also noted to have bilateral undescended testes. He developed bilateral chylothorax at 3 weeks of age, which resolved with low long-chain triglyceride, high-medium–chain triglyceride formula milk.

Investigations were initiated to determine the cause. Creatine kinase was 228 U/L. An open muscle biopsy histology done at 39 weeks’ corrected age revealed diffusely abnormal and centrally placed nuclei in the majority of the myofibers . This picture was highly suggestive of a congenital centronuclear myopathy. Genetic tests confirmed XLMTM. The mutation was c.1189dupT p.Tyr397fs and results in a premature termination of the MTM1 protein and is predicted to be pathogenic.

The patient’s parents were counseled extensively regarding the 2 genetic conditions in the infant that would significantly affect his quality of life. After several multidisciplinary team meetings, a joint decision was undertaken by the medical teams and parents for reorientation of care, and the infant died at 2½ months of age. Both parents had genetic investigations that revealed that the mother was a carrier for MTM1 but not DMD. The father had no abnormalities detected.

source: https://pediatrics.aappublications.org/content/146/3/e20182879?rss=1