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DNA Deletions in Dystrophin Gene and Clinical Phenotype of Duchenne Muscular Dystrophy in the San-in Area, Japan
Tatsuo Nitta, Kenzo Sato†, Kenji Nakashima, Kousaku Ohno‡, Kenzo Takeshita*, Yumi Yamaguchi†, Shiro lkawa§, Hideya Endo† and Kazuro Takahashi
Division of Neurology and *Division of Child Neurology, Institute of Neurological Sciences, †Department of Molecular Biology, ‡Department of Neurobiology and §Department of Clinical Laboratory Medicine, Faculty of Medicine, Tottori University, Yonago 683, Japan
For the purpose of genetic counseling of patients with Duchenne muscular dystrophy (DMD), we examined DNA deletion in the dystrophin gene on 35 patients with DMD in the San-in area, an ideal district for studying genetic diseases. The deletions in the gene were found in 17 patients by Southern blot analyses using six cDNA probes covering the entire 14 kb transcript. Most of the deletions were located in the two hot spot regions, as shown by cDMD1-2a and cDMD8 probes. In addition, the majority of deletions in the gene was out-of-frame type, even in the groups with milder clinical phenotypes. The correlation between clinical grade of DMD and the position of DNA deletion in the gene fit the reading frame model only in 64.7% of our cases. In the present study, however, rather than the position of deletion, extent of the deletion in the gene appeared to be more significantly related to the severity of this disease.
Key words: DNA deletion; dystrophin gene; progressive muscular dystrophy; Southern blot analysis