KCNQ4 and Noonan syndrome: Forty-three couples carried pathogenic variants in autosomal recessive non-syndromic HL genes, GJB2 and SLC26A4, and one case carried a variant in the autosomal dominant non-syndromic HL gene, KCNQ4. Three cases were diagnosed with syndromic HL, including one case of Noonan syndrome (PTPN11), one case of Waardenburg syndrome (PAX3), and one case of usher syndrome (USH2A).