Chromosomal localization of the human hexabrachion (tenascin) gene and evidence for recent reduplication within the gene.

Using analysis of rodent-human somatic cell hybrids as well as in situ hybridization of hexabrachion cDNA probes to normal human metaphase chromosomes, we have localized the human hexabrachion gene to chromosome 9, bands q32-q34. We also put forward the hypothesis that there has been a recent reduplication of a small segment of the human hexabrachion gene. We support this hypothesis by comparison of codon usage in this segment of the gene to codon usage in the remainder of the gene. This hypothesis is also supported by comparison of the sequence of human hexabrachion to that of the chicken hexabrachion. In addition, the latter comparison shows that the reduplication most likely occurred after the divergence of mammalian and avian species.