Altogether, these analyses identified the existence of only three of the theoretically possible four distinct TIMP-1 glycosylation variants in healthy donors and PC patients: the fully glycosylated form (TIMP-1glyc1/1), only one of the two possible monoglycosylated forms glycosylated at N78 (TIMP-1glyc0/1), and the nonglycosylated form (TIMP-1glyc0/0). Here, TIMP1 is linked to pachyonychia congenita.