Heterozygous Sall1 knock-out mice have no phenotype, whereas ΔZn2-10 Sall1 mice, which produce a truncated protein, show some TBS features such as kidney malformations and hearing loss, suggesting a gain-of-function or dominant-negative effects of SALL1 variants involved in TBS [16–18]. This evidence concerns the gene SALL1 and Townes-Brocks syndrome.