Fragile X carrier screening and FMR1 allele distribution in the Japanese population

Susumu Otsuka, Yumiko Sakamoto, Haruhiko Siomi, Mituo Itakura, Kenji Yamamoto, Hideo Matumoto, Tsukasa Sasaki, Nobumasa Kato, Eiji Nanba

研究成果: Article査読

47 被引用数 (Scopus)


Fragile X syndrome (FXS), which is the most common form of familial mental retardation, is caused by the expansion of the CGG repeat in the FMR1 gene on the X chromosome. Previous studies have suggested that as compared to other populations, Japanese have a lower prevalence of FXS. In addition, in the normal population, there are no carriers who have the premutation allele. We analyzed a total of 946 normal Japanese (576 males and 370 females) and attempted to estimate the frequency of the FMR1 allele. Within this population, we found that 1,155 alleles were in the normal range (less than 40 CGG repeats) and had a modal number of 27 repeats (35.75%). No carriers with premutations (55-200 CGG repeats) were observed in this normal population. We also identified six intermediate-sized alleles (40-54 CGG repeats), with a reported incidence of 1 in 103 males and 1 in 324 females. However, this allele frequency was different from that previously reported for the Japanese population. Since data from previous studies has suggested that FXS might possibly be associated with the genetic mechanism of autism, we also analyzed the length of the CGG repeats in 109 autistic patients. In all cases the CGG repeat numbers were within the normal range (16-36 repeats) and no individuals presented with expanded premutation or intermediate alleles. This finding indicates that the length of the CGG repeat within the FMR1 is unlikely to be responsible for autism in Japanese.

ジャーナルBrain and Development
出版ステータスPublished - 2010 2月

ASJC Scopus subject areas

  • 小児科学、周産期医学および子どもの健康
  • 発達神経科学
  • 臨床神経学


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