Deafness, X-Linked 4, also known as dfnx4, is related to deafness, x-linked 3 and deafness, x-linked 1. An important gene associated with Deafness, X-Linked 4 is SMPX (Small Muscle Protein X-Linked), and among its related pathways/superpathways are Pentose phosphate pathway and PRPP biosynthesis. Related phenotypes are sensorineural hearing impairment and high-frequency hearing impairment