Metformin in Children and Adults With Fragile X Syndrome

Fragile X Syndrome (FXS) is caused by loss of FMR1 expression on the X chromosome that leads to increased mRNA translation, which results in hyperactivation of ERK (extracellular signal-regulated kinase) and mTORC1 (mechanistic target of rifampicin complex 1) signalling and consequently in synaptic dysfunction and neurological development. There is presently no cure for FXS. Recent studies suggest that metformin (a widely prescribed drug for type II diabetes in children and adults) which crosses the blood-brain barrier, corrects various neurological and behavioral FXS phenotypes by normalizing ERK signaling, EIF4E phosphorylation and lowering expression of MMP9 to normal. Since this drug has not been previously used specifically for treatment of FXS (only few cases reported), the investigators propose an open-label trial of metformin in children and adults with FXS to better understand the safety and efficacy in both behavior and cognition.