Notable positive examples include dominant erythropoietic protoporphyria, caused by mutations in the FECH gene, and dominant elliptocytosis, due to mutations in SPTA1. In these disorders, an imbalance of expression between the wild-type and the mutated alleles causes the manifestation of the symptoms [25]–[27]. This evidence concerns the gene FECH and erythropoietic protoporphyria.