As the DA receptor D2R has been identified as a binding partner of NCS-1 (Kabbani et al., 2002) and DA D1R is affected by the loss of function of FMRP (Wang et al., 2008), we thought it was relevant to include D1R and D2R in the gene expression profile and study the mRNA level of this gene in relation to FXS pathology and FD44 treatment. Here, DRD1 is linked to fragile X syndrome.