MTM1 GENE-MUTATIONS IN JAPANESE PATIENTS WITH THE SEVERE INFANTILE FORM OF MYOTUBULAR MYOPATHY

The severe infantile form of myotubular myopathy is a fatal muscle dis ease that predominantly affects male infants and is characterized by s evere weakness and hypotonia from birth. X-linked myotubular myopathy was found to be associated with mutations in the MTM1 gene in Xq28 enc oding the putative tyrosine phosphatase, myotubularin. We screened the MTM1 gene for mutations in seven Japanese patients (six males and one female) who had the diagnosis of severe infantile farm of myotubular myopathy. We found five mutations, including three novel mutations bas ed on sequence analysis of RT-PCR fragments covering the entire open r eading frame. Two patients tone male and one female), who had similar clinicopathologic features, did not have any mutation in the MTM1 gene open reading frame, suggesting that they may have had an autosomal re cessive disease. (C) 1998 Elsevier Science B.V. All rights reserved.