Close linkage of retinoic acid receptor genes with homeobox- and keratin-encoding genes on paralogous segments of mouse chromosomes 11 and 15.

Retinoic acid is essential for normal development and growth of structures such as head and limbs, and it can act as morphogen or teratogen. Retinoic acid induces expression of genes such as the homeobox genes and keratin type I and type II genes. Retinoic acid receptors are nuclear transcription factors that play a key role in retinoid physiology. As part of the characterization of retinoic acid receptor gene family, linkage of genes encoding the three receptors was determined by using interspecific backcross and recombinant inbred strain analysis of restriction fragment variants. Retinoic acid receptor alpha is located on mouse Chromosome (Chr) 11 near the homeobox-2 complex and the keratin type I gene complex, whereas retinoic acid receptor gamma is on mouse Chr 15 near the homeobox-3 complex and the keratin type II complex. Close genetic proximity of these functionally related genes may be significant. We confirmed assignment of retinoic acid receptor beta to the centromeric portion of Chr 14. These linkage assignments provide further evidence for duplicated segments in the mouse genome.