MUC4 and endometriosis: Published studies have reported that polymorphisms in MUC4 are associated with susceptibility to lung cancer, endometriosis development and endometriosis-related infertility [37, 38]; homozygous G allele carriers of the MUC4 SNP rs842225 were reported to have a decreased risk of lung cancer in a Han Chinese population [35, 37, 38].