For example, Romey et al. described the case of a complex allele [c.-234T>A;p.Ser549Arg] ([c.-234T>A;p.S549R]) variant of c.-234T>A which enhances the activity of the CFTR promoter, reducing the severity of the phenotype caused by p.Ser549Arg, causing CF [33]. Here, CFTR is linked to cystic fibrosis.