2001 Fiscal Year Final Research Report Summary
Genetic analysis of patients with spinal muscular atrophy
| Project/Area Number |
11670744
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Pediatrics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAKAKIHARA Youichi Univ. of Tokyo, Faculty of Medicine, Lecturer, 医学部・附属病院, 講師 (10143463)
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| Co-Investigator(Kenkyū-buntansha) |
KUBOTA Masaya Univ. of Tokyo, Faculty of Medicine, Assistant Professor, 医学部・附属病院, 助手 (90251272)
SAITO Makiko Univ. of Tokyo, Faculty of Medicine, Assistant Professor, 医学部・附属病院, 助手 (20225733)
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| Project Period (FY) |
1999 – 2001
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| Keywords | spinal muscular atrophy / SMN1 / SMN2 |
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| Research Abstract |
Spinal muscular atrophy (SMA) is a frequent autosomal recessive neurodegenerative disorder with progressive weakness and atrophy of voluntary muscles. The survival motor neuron gene (SMN) is present in two highly homologues copies (SMN 1 and SMN 2) on chromosome 5q13. Homozygous deletion of exons 7 and 8 of SMN 1 is responsible for SMA. In SMA patients, SMN 2 partially compensate the lack of SMN 1. Previously we reported the relative high incidence of large deletion including SMN1 region in Japanese SMA type I patients. The purpose of this study to demonstrate another genetic back ground of Japanese SMA type I patients investigating the the SMN 1 to SMN 2 ratio in carriers. As expected, in normal individuals there is one copy of each gene on a chromosome (SMN1/SMN2 was 1). In this study we determined the SMN1/SMN2 ratios of 14 parents and one carrier sibling of Japanese type I SMA patients with homozygous deletion of exons 7 and 8 of SMN1. We found that the SMN1/SMN2 ratio was 0.5 or 1 in eleven (73.3%) carriers. Residual four carriers had the SMN1/SMN2 ratio of 1/3. This finding supports the idea that the deletion rather than conversion is the main genetic event in type I SMA. For further insight into the characteristic genetic background of SMA in Japan, identification of gene copy number is essential.
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