Prader-Willi syndrome (PWS) results from inactivation of a domain on the paternal chromosome 15 while the same domain on chromosome 15 that is of maternal origin is normally inactivated. This situation in Prader-Willi patients is therefore associated with complete silencing of a relatively large number of genes that are located in this domain. This silencing of the genes is therefore implicated in the various symptoms observed in Prader-Willi patients. It is presumed that the genes of the domain on the maternal chromosome 15 are intact and perfectly normal but unfortunately dormant. The question is, how can be wake these genes up? Answering this question might not be simple, but we think that it is feasible because there is one switch (PWS-IC), that, if turned on, might be sufficient to activate the genes on the maternal chromosome. We identified a specific protein that is involved in the turning off of this switch. We propose here to turn off the gene that codes for this specific protein and thereby repress its production. We hope that in the absence of this protein in Prader-Willi syndrome patient cells, we will be able to turn on the switch (PWS-IC) on the intact maternal chromosome and consequently turn on the paternal genes on the maternal chromosome. We will perform such an experiment in lymphoblasts of a PWS patient that will, if successful, lay the foundation for a novel potential therapeutic approach.