Jill
                    
                    
                    
                    
                    
                    
                    
                        
                        
                        According to my medical terminology book, it is Huntington's chorea - a herediatary nervous disorder involving bizarre, abrupt, involuntary movements, which are termed choreiform. Chorea  is a nervous disorder in children, marked by irregular and uncontrollable muscle movements.  The blond girl on the show Allie McBeal has that disease.  The girl twitches all the time and even yelps.