Amelogenesis imperfecta (AI) is a relatively rare group of inherited tooth development disorders characterized by defects of dental enamel that are not associated with any other generalized defect. It usually involves all teeth in the primary and permanent dentitions. Its etiology is related to the alteration of genes involved in the process of formation and maturation of the enamel. This genetic alteration can be divided into three main types: hypoplastic, hypocalcified and hypomaturation, according to the clinical characteristics of the enamel, which reflect the stage of formation at which the enamel was affected. Each type can be subdivided into subtypes depending on the mode of inheritance, as well as on the clinical and radiographic aspect of the enamel defect, although in some cases characteristics overlap, making classification difficult. The hypomaturation type involves an abnormality during the maturation stage of enamel formation, resulting in a weak, creamy-brown opaque enamel that fails prematurely after tooth eruption.
In two consanguineous Omani families affected with hypomaturation-type amelogenesis imperfecta, El-Sayed et al. (2009) identified two mutations in the WDR72 gene. Male patient from one of the two families was found to be homozygous for a nonsense mutation (c.2934G>A; p.W978X). While the another family with affected brother and sister was found to be homozygous for a deletion of a single base pair in exon 16 (c.2857Adel.), which leads to a terminal frame shift (p.S953VfsX20).