Andreia Carvalho, Carmen Costa, Miguel Pinto, Ricardo Taipa, Ana Gonçalves, Márcia E Oliveira, Sofia Ferreira, Joana Afonso Ribeiro
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X-Linked Myotubular Myopathy: A Novel Mutation Expanding the Genotypic Spectrum of a Phenotypically Heterogeneous Myopathy.
X-linked myotubular myopathy (XLMTM), a centronuclear congenital myopathy secondary to pathogenic variants in the MTM1 gene encoding myotubularin, is typically recognized for its classic and severe phenotype which includes neonatal hypotonia, severe muscle weakness, long-term ventilator dependence, markedly delayed gross motor milestones with inability to independently ambulate, and a high neonatal and childhood mortality. However, milder congenital forms of the condition and other phenotypes are recognized. We describe a 6-year-old boy with a mild XLMTM phenotype with independent gait and no respiratory insufficiency even in the neonatal period. The child has a hemizygous novel splice site variant in the MTM1 gene (c.232-25A > T) whose pathogenicity was confirmed by cDNA studies (exon 5 skipping) and muscle biopsy findings. We also compared the phenotype of our patient with the few reported cases that presented a mild XLMTM phenotype and no respiratory distress at birth, and discussed the potential mechanisms underlying this phenotype such as the presence of residual expression of the normal myotubularin transcript.
期刊介绍:
The Journal of Pediatric Genetics is an English multidisciplinary peer-reviewed international journal publishing articles on all aspects of genetics in childhood and of the genetics of experimental models. These topics include clinical genetics, molecular genetics, biochemical genetics, medical genetics, dysmorphology, teratology, genetic counselling, genetic engineering, formal genetics, neuropsychiatric genetics, behavioral genetics, community genetics, cytogenetics, hereditary or syndromic cancer genetics, genetic mapping, reproductive genetics, fetal pathology and prenatal diagnosis, multiple congenital anomaly syndromes, and molecular embryology of birth defects. Journal of Pediatric Genetics provides an in-depth update on new subjects and current comprehensive coverage of the latest techniques used in the diagnosis of childhood genetics. Journal of Pediatric Genetics encourages submissions from all authors throughout the world. The following articles will be considered for publication: editorials, original and review articles, short report, rapid communications, case reports, letters to the editor, and book reviews. The aim of the journal is to share and disseminate knowledge between all disciplines in the field of pediatric genetics. This journal is a publication of the World Pediatric Society: http://www.worldpediatricsociety.org/ The Journal of Pediatric Genetics is available in print and online. Articles published ahead of print are available via the eFirst service on the Thieme E-Journals platform.