For example, the identification of the causal variant of cleft lip and palate IRF6:NM_006147.4:c.179 G > C;p.(Trp60Ser), heterozygous in family F750 was challenging because the phenotype varied widely between frank cleft lip and palate to lip pits that were not always apparent clinically due to the use of cosmetic fillers. Here, IRF6 is linked to cleft lip.