Syndromic SNHL included Stickler (18%, n = 4), Usher (18%, n = 4), Alport (9%, n = 2), Baraitser-Winter (4.5%, n = 1), AIFM1-related (4.5%, n = 1), Branchiootorenal (BOR 1) (9%, n = 2), Hypoparathyroidism, Sensorineural deafness, and Renal dysplasia (HDR) (4.5%, n = 1), Perrault (4.5%, n = 1), Donnai Barrow (4.5%, n = 1), Kearns-Sayre (4.5%, n = 1), RTN4IP1-related (4.5%, n = 1), Branchiootic (BOR 3) (4.5%, n = 1), Pendred (4.5%, n = 1), and multiple sulfatase deficiency (4.5%, n = 1) syndromes (Additional file 1: Table S1). This evidence concerns the gene RTN4IP1 and Down syndrome.