Expression of Wnt/β-Catenin Pathway Components in Fragile X Syndrome Patients: Evidence of Pathway Dysregulation

Background: The absence of Fragile X Mental Retardation Protein (FMRP) causes Fragile-X syndrome (FXS), the most frequent form of inherited intellectual disability. Recent evidence suggests that individuals with FXS have a decreased risk of developing cancer, and overexpression of FMRP has been linked to cancer progression. The aim of the present study is to examine the expression of multiple Wnt/β-catenin pathway components in FXS patients. Methods: Fifteen molecularly confirmed FMR1 full-mutation males and 15 age-matched male controls were studied. Total RNA from peripheral blood mononuclear cells (PBMCs) was used to quantify the expression of 15 Wnt/β-catenin pathway genes by real-time PCR (qPCR), and Western blot analysis was performed to assess β-catenin protein in nuclear and cytoplasmic PBMC fractions. Results: WNT7A, PPP2R5C, FOSL1, and JUN showed significantly reduced expression in FXS patients versus controls. Western blot consistently detected a ~60–65 kDa immunoreactive band, rather than full-length β-catenin, in cytoplasmic fractions of both groups, with nuclear presence in a subset of patients. Conclusions: These findings suggest dysregulation of the Wnt/β-catenin signaling pathway in FXS patients and identify a potentially novel molecular alteration in β-catenin that deserves further investigation.