Cross-disorder genome-wide analyses suggest a complex genetic relationship between Tourette's syndrome and OCD.
Yu D, Mathews CA, Scharf JM, Neale BM, Davis LK, Gamazon ER, Derks EM, Evans P, Edlund CK, Crane J, et al. Am J Psychiatry. 2015 Jan; 172(1):82-93. Epub 2014 Oct 31.