Neuropediatrics 2005; 36 - P8
DOI: 10.1055/s-2005-867993

A rare differential diagnosis of severe neonatal muscular hypotonia with respiratory distress: Myotubular myopathy (MTM 1) with detection of a new complex mutation in myotubularin gene

V Boda 1, D Fischer 2, S Vlaho 1, K Bauer 2, M Kieslich 1
  • 1Kinderklinik der Johann Wolfgang Goethe Universität, Pädiatrische Neurologie, Frankfurt am Main
  • 2Kinderklinik der Johann Wolfgang Goethe Universität, Neonatologie, Frankfurt am Main

Objective: The reason for postnatal respiratory distress in newborns may be muscular hypotonia. We describe a male newborn whose cause for postnatal apnoea was a myotubular myopathy.

Case report: Marrocan, healthy parents, no consanguinity. The mother has 2 healthy brothers and sisters, 4 other brothers died at the first day of life. Pregnancy and birth without complications, postnatal apnoea of the newborn. Umbilical pH 7,25. Severe muscular hypotonia with myopathic face, severely decreased tendon reflexes, decreased swallowing and coughing reflexes. No loss of other brain stem reflexes. Elongated, narrow face, long fingers/toes, no other stigmata. No seizures. Normal MRI. Muscle biopsy: Centronuclear myopathy. Mutationanalysis showed a new complex mutation (deletion and insertion of myotubularin gene on the X-chromosome).

Discussion: Centronuclear myopathies (centralized nuclei of myocytes in muscle biopsy) can be inherited autosomal dominant and recessive and x-linked recessive. In the most cases the x-linked form is the one with the severest clinical symptoms and is called Myotubular Myopathy (MTM1). The children are presenting with severe connatal muscular hypotonia (“floppy infant“) and typically with postnatal respiratory distress. The clinical course is dependent on complications due to the muscular hypotonia, but nonprogressive. Milder forms are discribed. The mental outcome primarily is normal. The mutationanalysis of our patient showed a new, complex mutation in the Myotubularin gene. Up to now there is no phenotype/genotype-correlation described in the literature.

Conclusions: In the differential diagnosis of a newborn presenting with postnatal respiratory distress neuromuscular diseases should be included, especially when no pre- or intrapartal complications are documented. In boys the rare X-linked myotubular myopathy could be one cause.