Description of a new kind of MHC DNA sequence in Saguinus oedipus (cotton-top tamarin).

The MHC class I genes of the New World primate the cotton-top tamarin (Saguinus oedipus) are an exception to the high polymorphism and variability usually displayed by this multigene family. In the present work, the cloning and sequencing of a new pseudogene, tentatively named Saoe-Mhc-N4, in this primate species are reported. This new sequence has two characteristic deletions at exon 2, making it very unlikely that any putative protein from this sequence was an antigen-presenting molecule. Comparison of intron 1, intron 2, partial exon 1, exon 2 and partial exon 3 showed little similarity with those of classical class I genes and pseudogenes in S. oedipus and in other primates. Phylogenetic analysis grouped this Saoe-Mhc-N4 sequence with other pseudogenes in S. oedipus. Thus, it seems that Saoe-Mhc-N4 is an inactivated gene or a pseudogene which has been originated by the common process of duplication and subsequent inactivation of MHC class I loci in this primate species.