They found that numerous deafness-related genes (e.g. Col9a2, Lmx1a, and Sox10) were downregulated, and single-cell transcriptome data from Chd7KO/+ organoids also showed that some deafness-related genes (e.g. Six1, Ush1c, and Strc) were downregulated in HCs, implying that. Here, COL9A2 is linked to deafness.