Intragenic copy number variation within human epiplakin 1 (EPPK1) generates variation of molecular size of epiplakin

Epiplakin is a versatile cytolinker protein that is expressed in the epithelium, including the epidermis, several glands, and digestive organs [1]. Human epiplakin consists of 13 B domains that are homologous to the B domain found in the carboxy-terminal region of desmoplakin; the last five B domains at the carboxy-terminal end, together with their associated linker regions, are highly conserved [1] (Fig. 1A). The mRNA of epiplakin is transcribed from the third exon of the epiplakin gene (EPPK1) [2,3] (Fig.