While FOXL1 (and FOXC2) have been associated with osteoporosis in humans, and the co-occurrence of otosclerosis and osteoporosis has been reported [65,66,76], we did not find any defects in development of the larval zebrafish axial skeleton in foxl1 or foxc1b (FOXC2 homolog) mutants. Here, FOXC2 is linked to osteoporosis.