They predicted that these species would have copies of the gene that codes for the tooth-specific enamelin protein, but this gene would show evidence of molecular decay in these species.
"We predicted that enamel-specific genes such as enamelin would show evidence in living organisms of molecular decay because these genes are vestigial and no longer necessary for survival," he added.
The enamelin gene, ENAM, has been mapped with different techniques to the same region on chromosome 4q as AIH2 and AMBN, suggesting that this region could contain a cluster of genes encoding enamel proteins.
(9.) Rajpar MH, Harley K, Laing C, Davies RM and Dixon MJ (2001) Mutation of the gene encoding the enamel-specific protein, enamelin, causes autosomal-dominant amelogenesis imperfecta.