ERCC6 and Cowden syndrome 1: This is in contrast to our study in which our cohort of 21 patients with CS from a Han Chinese population included 13 patients with CS-A (61.90%) as well as 5 patients with CS-B (23.80%) and 3 patients with no discernible mutation (14.30%) in ERCC6 or ERCC8. So far, no ERCC6 founder mutation or high frequency mutation has been reported in Chinese population.