Expression of FMR1, FXR1, and FXR2 genes in human prenatal tissues - Archive ouverte HAL Access content directly
Journal Articles Journal of Neuropathology and Experimental Neurology Year : 1999

Expression of FMR1, FXR1, and FXR2 genes in human prenatal tissues

Cendra Agulhon
  • Function : Author
Patricia Blanchet
  • Function : Author
Alexandra Kobetz
  • Function : Author
Dominique Marchant
  • Function : Author
Nicole Faucon
  • Function : Author
Pierre Sarda
  • Function : Author
Claude Moraine
  • Function : Author
Annie Sittler
  • Function : Author
Alain Malafosse
  • Function : Author
Marc Abitbol
  • Function : Author


We analyzed the distribution of FMR1, FXR1, FXR2 mRNA, and FMRP in whole normal human embryos and in the brains of normal and fragile X fetuses. The distributions of mRNA for the 3 genes in normal whole embryos and in the brains of normal male and female carrier fetuses were similar, with large amounts of mRNA in the nervous system and in several non-nervous system tissues. No FMR1 (mRNA and protein) was detected and no evident neuropathologic abnormalities found in the brains of male carrier fetuses, suggesting that the FMR1 product (FMRP) may have no crucial function in early stages of nervous system development. FXR1 and FXR2 mRNA had the same distribution and similar intensity in the brains of normal and pathologic fetuses (female and male carriers). The coexpression in the same tissues of FMR1, FXR1, and FXR2, associated with the normal expression of FXR1 and FXR2 and the absence of obvious neuropathological abnormalities in pathological brains, supports the notion that the FXR1 and FXR2 proteins partially compensate for FMRP function. However, the absence of significant overexpression of FXR1 and FXR2 in pathological brains suggests that these genes do not compensate for the lack of FMR1 expression. Alternatively, FMR1, FXR1, and FXR2 proteins may not have compensatory functions, but instead may regulate functions by hetero or homo oligomerization, as suggested by other studies. Thus, a dominant negative effect of abnormal multimeric protein complexes lacking FMRP (e.g. by modification of FXR1 and FXR2 protein functions) may result in the fragile X syndrome phenotype.

Dates and versions

hal-04022402 , version 1 (09-03-2023)



Cendra Agulhon, Patricia Blanchet, Alexandra Kobetz, Dominique Marchant, Nicole Faucon, et al.. Expression of FMR1, FXR1, and FXR2 genes in human prenatal tissues. Journal of Neuropathology and Experimental Neurology, 1999, 58 (8), pp.867-880. ⟨10.1097/00005072-199908000-00009⟩. ⟨hal-04022402⟩
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