Organization and evolution of the flavin-containing monooxygenase genes of human and mouse

Abstract

We have identified, for the first time, a mouse Fmo6 gene. In addition, we describe a novel human FMO gene cluster on chromosome 1, located 4 Mb telomeric of the original cluster. The novel cluster contains five genes, all of which exhibit characteristics of pseudogenes. We propose the names FMO 7P, 8P, 9P, 10P and 11P for these genes. We also describe a novel mouse gene cluster, located approximately 3.5 Mb distal of the original gene cluster on Chromosome 1. The novel mouse cluster contains three genes, all of which contain full-length open-reading frames and possess no obvious features characteristic of pseudogenes. One of the genes is apparently a functional orthologue of human FMO9P. We propose the names Fmo9, 12 and 13 for the novel mouse genes. Orthologues of these genes are also present in rat. Sequence comparisons and phylogenetic analyses indicate that the novel human and mouse gene clusters arose, not from duplications of the known gene cluster, but via a series of independent gene duplication events. The mammalian FMO gene family is thus more complex than previously realised.