Pendrin is also implicated in DFNB4, an autosomal recessive form of nonsyndromic deafness [79]. SLC26A4 mutations that are clinically associated with Pendred syndrome cause complete loss of transport function when studied in heterologous expression systems, mostly due to retention in various intracellular compartments, whereas those exclusively associated with DFNB4 have residual transport activity [80]. Here, SLC26A4 is linked to Pendred syndrome.