A genomic region encompassing a cluster of olfactory receptor genes and a myosin light chain kinase (MYLK) gene is duplicated on human chromosome regions 3q13-q21 and 3p13

The olfactory receptor (OR) multigene family is widely distributed in the h uman genome. We characterize here a new cluster of four OR genes (HGMW-appr oved symbols OR7E20P, OR7E6P, OR7E21P, and OR7E22P) on human chromosome 3p1 3 that is contained in an similar to 250-kb region. This region has been ph ysically mapped, and a 106-kb portion containing the OR genes has been sequ enced. All the OR sequences are disrupted by frameshifts and stop codons an d appear to have arisen through local duplications. A myosin light chain ki nase pseudogene (HGMW-approved symbol MYLKP) lies at one end of the OR gene cluster. Sequences spanning the entire region are also present at 3q13-q21 , the site of the functional MYLK gene. This region duplicated locally befo re the divergence of primates, and the two paralogous copies were later sep arated to sites on either side of the centromere. This study increases our understanding of the evolution of the human genome. The 3p13 cluster is the first example of a tandem array of OR pseudogenes, and duplications of suc h clusters may account for the accumulation of a large number of pseudogene s in the human genome. (C) 1999 Academic Press.