FZD6 and Nail dysplasia: For instance, there is a strong correlation between frameshift mutations of FZD6 and neural tube defects, such as failure of neural tube closure along the entire body axis, suggesting the importance of Fzd6 in directing cell migration and cell polarity during brain morphogenesis.25 FZD6 is also important for nail development, since homozygous frameshift mutations result in the onset of a rare form of nail dysplasia.