CLDN16 and amelogenesis imperfecta: Indeed, we demonstrated that loss-of-function mutations in Claudin-16 and -19 (CLDN16 and 19) genes, initially identified to cause Familial Hypomagnesemia with Hypercalciuria and Nephrocalcinosis (FHHNC), also resulted in Amelogenesis Imperfecta (AI) (Bardet et al., 2016; Yamaguti et al., 2017).