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Runx2 Tandem Repeats And The Evolution Of Facial Length In Placental Mammals, Marie Pointer, Jason Kamilar, Vera Warmuth, Stephen Chester, Frédéric Delsuc, Nicholas Mundy, Robert Asher, Brenda Bradley

Jason M. Kamilar

Background When simple sequence repeats are integrated into functional genes, they can potentially act as evolutionary ‘tuning knobs’, supplying abundant genetic variation with minimal risk of pleiotropic deleterious effects. The genetic basis of variation in facial shape and length represents a possible example of this phenomenon. Runt-related transcription factor 2 (RUNX2), which is involved in osteoblast differentiation, contains a functionally-important tandem repeat of glutamine and alanine amino acids. The ratio of glutamines to alanines (the QA ratio) in this protein seemingly influences the regulation of bone development. Notably, in domestic breeds of dog, and in carnivorans in general, the ratio …