What is the connection between red hair and Tourette syndrome?

The many faces of Gilles de la Tourette syndrome

“…The only case reports on GTS which are now published are of subjects such as deep brain stimulation (DBS) or a rare possible GTS genetic 'variant' or chromosomal abnormality which may give clues as to the genetic causes. Current research includes cohorts of patients having had successful DBS and fMRI, diffusion tensor MRI, neuropsychological profiles of cohorts, and even suggestions of a putative link between red hair and GTS [2]! It is now well known that certain psychopathologies occur in the majority of GTS patients and that some of these include attention deficit disorder (ADHD), obsessive compulsive disorder and behaviors, autistic spectrum disorder, and depression [3].…”