| Project/Area Number |
05807211
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Human genetics
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| Research Institution | University of Tsukuba |
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Principal Investigator |
ARINAMI Tadao Institute of Basic Medical Sciences.Assoc.prof., 基礎医学系, 講師 (10212648)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1994: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1993: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | fragile X syndrome / the FMR-1 gene / triplet repeat / mental retardation / 反復配列 / 突然変異率 / 創始者染色体 |
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| Research Abstract |
Distribution of the CGG repeat number of the FMR-1 gene was investigated in Japanese populations consisting of 801 apparently healthy subjects, 427 patients with mental retardation and 50 schizophrenics. The most frequent allele was CGG 29 copy number, followed by CGG 30 copy number in the apparently healthy Japanese. These are similar to the commonest allele, CGG 30 copy number, in Caucasians. The allele frequency of 36 copy number, which is rare in Caucasians, was found to be about 0.1 in Japanese general population. Haplotype analysis of FRAXAC1 and FRAXAC2 flanking FMR-1 showed that about half of the fragile X chromosones of Japanese fragile X patients have the same haplotype to that found in most of the alleles with CGG 36 copy number. Sequencing the CGG repeat region of the allele with 36 copy number revealed specific arrays including AGG-(CGG)_6 that is very rare in Caucasians. These arrays suggest that the allele of CGG 36 copy number and some proportion of founder chromosomes of Japanese fragile X mutation originated after the divergence of Asians and Caucasians. No premutation was found in 1600 FMR-1 gene in Japanese population. The distributions of CGG copy number in the mentally retarded subjects and schizophrenics were not significantly different from that of healthy subjects except for the alleles with full mutation in the mentally retarded males. The results by DNA analysis were completely consistent with those by chromosome analysis for fragile X syndrome in the mentally retarded population, indicating the low frequency of FRAXE associated mentally retardation.
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