Rhythm Pharmaceuticals Inc. (NASDAQ:RYTM) stock is higher on Thursday, after the company shared preliminary results from its exploratory Phase 2 trial of setmelanotide in patients with Prader-Willi syndrome (PWS).PWS is a rare genetic disorder characterized by muscle weakness and feeding difficulties in infancy. An insatiable hunger and tendency toward severe obesity starting in childhood could follow.PWS also involves delayed development, intellectual disability, behavioral issues, and physical traits, suc ...