It is challenging to determine the genotype-phenotype relationship in BOFS and Char Syndrome patients due to the small sample size and the large spectrum of mutations affecting TFAP2A and TFAP2B. With recent advances in site-targeted mutagenesis in the C. elegans genome, it is an exciting possibility to generate worm strains carrying mutations of conserved residues in BOFS and Char Syndrome. The gene discussed is TFAP2B; the disease is Branchio-oculo-facial syndrome.