In OPMD, a short abnormal polyalanine expansion in the ubiquitous RNA-binding protein PABPN1 (Poly(A)-Binding Protein Nuclear 1) leads to muscle dysfunction with clinical manifestations primarily restricted to a limited group of muscles: eyelid and pharyngeal muscles are the first affected muscles leading, respectively, to ptosis and dysphagia [64]. Here, PABPN1 is linked to ptosis.