SLC26A4 and Menkes disease: Another recent study found that sporadic MD patients had enrichment of missense mutations in a variety of genes associated with SNHL including GJB2 (connexin 26 deafness), SLC26A4 (Pendred syndrome), and USH1G (Usher 1C) compared to controls, which the authors postulate may have an additive effect on the MD phenotype (17, 18).