Susana Zanello, Universities Space Research Association scientist at NASA's Johnson Space Center in Houston,
examined eye tissue for changes in gene expression in the retina — the sensory tissue at the back of the eye.
Eight HARs showed differences in their enhancer activity when the human mutations were present.4 These differences modify how genes were expressed in the developing limb (HAR2, 2xHAR114),
eye (HAR25), and central nervous system (2xHAR142, 2xHAR238, 2xHAR164, 2xHAR170, ANC516 / HARE5).4, 10 Because relatively few time points have been
examined, it is likely that an even higher percentage of the tested HARs are active enhancers at some point during embryonic development or in adult
tissues, possibly with human - chimp differences.