MONDAY, Dec. 19 (HealthDay News) -- Researchers studying zebrafish have uncovered a protein that controls skin pigmentation that is conserved in most vertebrates including humans, according to a report in the Dec. 16 issue of Science. The finding sheds light on the genetics of human skin tone.
Keith Cheng, M.D., Ph.D., of Penn State University College of Medicine in Hershey, Pa., and colleagues identified the pigment-controlling gene SLC24A5 through positional cloning. They found the gene differs in a lighter colored version of the zebrafish called "golden" and correlates with fewer and less dense melanosomes, the pigment-filled organelles inside melanocytes.
"Golden" fish have lighter stripes than wild-type zebrafish, which the researchers attributed to their truncated version of SLC24A5. Adding the wild-type version back to the "golden" variants led to fish with darker stripes. In addition, the human version of the gene could efficiently replace the zebrafish version suggesting the genes were closely related in all vertebrates.
Using the freely available HapMap database of human genetic variation, the authors found that people of European origin have a unique polymorphism in SLC24A5 that differs from Africans and East Asians.
"Our results suggest that distinguishing the functional genes from multiple candidates may require a combination of phylogenetic analysis, nonmammalian functional genomics, and human genetics," the authors write.
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