A large number of tandem repeats in the polymorphic epithelial mucin gene is associated with severe acne.

Polymorphic epithelial mucin (PEM) or MUC1 is a glycoprotein secreted from various epithelial gland tissues. In skin, PEM is detected in sweat glands and sebaceous glands by the DF3 monoclonal antibody. The gene of PEM includes an allele exhibiting length polymorphism due to a variable number of tandem repeats (VNTR); this is expressed co-dominantly, which may influence the microenvironment of the skin. The allelic size variation of the PEM gene was investigated in Japanese acne patients, atopic dermatitis patients, and healthy controls. The frequency of longer length alleles was significantly higher in severe acne patients.