Impaired intelligence, movement disorders and developmental delays are typical for a group of rare diseases that belong to GPI anchor deficiencies. Researchers from the University of Bonn and the Max Planck Institute for Molecular Genetics used genetic engineering methods to create a mouse that mimics these patients very well. Studies in this animal model suggest that in GPI anchor deficiencies, a gene mutation impairs the transmission of stimuli at the synapses in the brain. This may explain the impairments associated with the disease. The results are now published in the journal Proceedings of the National Academy of Sciences.