How did the Shar-pei get its famous wrinkles?

Scientists at the University of Washington analyzed the genetics of 10 dog breeds to locate the most-differentiated regions of their genes. They identified 155 distinct locations in the animals’ genetic code that could play a role in giving breeds their distinctive appearances. The results show some conspicuous physical traits, or phenotypes, such as height and coat color, can be traced to particular genes of beagles, border collies, dachshunds, poodles, among others. To characterize candidate genes in more detail, they focused on a region on chromosome 13 with evidence of selection in the Shar-Pei and containing three genes (SNTB1, FTSJ1, and HAS2). A distinguishing characteristic of the Shar-Pei is cutaneous mucinosis, or excessive skin wrinkling. The degree of skin folds correlates with high mucin content and elevated levels of hyaluronic acid. HAS2 codes for the hyaluronic acid synthase, the enzyme responsible for the production of the hyaluronic acid. To test the hypothesis that genetic variation in HAS2 contributes to skin wrinkling, they studied 32 wrinkled and 18 smooth-coated Shar-peis and found four small, but significant, differences in the HAS2 gene of the two skin types of the Shar-pei versus the other breeds. Rare mutations in human HAS2 gene have been described that lead to really severe wrinkling in humans, too. As well as giving insights into the Shar-pei, the research has also identified a raft of other locations in the dog genome that can now be investigated further to understand better why pedigree animals look the way they do.

Original article:
Akey JM et al. Tracking footprints of artificial selection in the dog genome.
Proc Natl Acad Sci U S A. 2010. 107(3):1160-5.

Summarized from the article of Jonathan Amos.
BBC News