PITX1 and Brachydactyly - elbow wrist dysplasia: Examples of enhancer adoption are Liebenberg syndrome (MIM 186550), a homeotic arm-to-leg transformation, in which deletion and rearrangement brings two active enhancers closer to the PITX1 (paired-like homeodomain 1) promoter (28,31) or holoprosencephaly spectrum disorder and severe upper limb syndactyly with lower limb synpolydactyly due to the relocation of the SHH transcription unit near a limb bud enhancer (49).