J Clin Neurol.  2013 Jan;9(1):57-60. 10.3988/jcn.2013.9.1.57.

Two Cases of X-Linked Myotubular Myopathy with Novel MTM1 Mutations

• Lee EH
• Yum MS
• Park SJ
• Lee BH
• Kim GH
• Yoo HW
• Ko TS

• KMID: 2287572
• DOI: http://doi.org/10.3988/jcn.2013.9.1.57

Abstract

BACKGROUND
Myotubular myopathy (MTM) is a congenital myopathy characterized by centrally placed nuclei in muscle fibers. Mutations in the myotubularin 1 gene (MTM1) have been identified in the most of the patients with the X-linked recessive form.
CASE REPORT
This report describes two male infants with X-linked MTM (XLMTM). Both patients presented with generalized hypotonia and respiratory difficulties since birth. We did not perform a muscle biopsy in either patient, but their conditions were diagnosed by genetic testing of MTM1. One splicing mutation, c.63+1G>C, and a frame-shift mutation, c.473delA (p. Lys158SerfxX28), were identified. Neither mutation has been reported previously.
CONCLUSIONS
Genetic testing for MTM1 is helpful for the differential diagnosis of floppy male infants. We suggest that advanced molecular genetic testing may permit a correct diagnosis while avoiding invasive procedures.

Keyword

myotubular myopathy; X-linked; MTM1; centronuclear myopathy; muscle hypotonia

MeSH Terms

Biopsy
Diagnosis, Differential
Genetic Testing
Humans
Infant
Male
Molecular Biology
Muscle Hypotonia
Muscles
Muscular Diseases
Myopathies, Structural, Congenital
Parturition
Protein Tyrosine Phosphatases, Non-Receptor
Protein Tyrosine Phosphatases, Non-Receptor

Figure

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  Fig. 1 A hemizygous c.63+1G>C mutation of MTM1 in case 1. MTM1: mutations in the myotubularin 1 gene.

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  Fig. 2 Deletion at nucleotide 473 in exon 6 of MTM1 in case 2 and his mother. MTM1: mutations in the myotubularin 1 gene.

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