- Analysis of alkaptonuria (AKU) mutations and polymorphisms reveals that the CCC sequence motif is a mutational hot spot in the homogentisate 1,2 dioxygenase gene (HGO). Beltrán-Valero de Bernabé, D., Jimenez, F.J., Aquaron, R., Rodríguez de Córdoba, S. Am. J. Hum. Genet. (1999)