Compared with isogenic control brain organoids, FXS brain organoids exhibited larger size and more GFAP-positive glial cells, which is consistent with the observed effect of the FMR1 gene on neural progenitor cell proliferation under 2D culture conditions, suggesting that the brain organoid model can be used to explore the pathological mechanism of X-linked intellectual disability and provide a new platform for the treatment of such diseases. The gene discussed is FMR1; the disease is fragile X syndrome.