Mirror hand syndrome AKA ulnar dimelia is a rare congenital anomaly of the upper limb. It is characterized by: - duplication of ulna - absence of radius - symmetrical polydactyly Reference: https://www.sciencedirect.com/science/article/abs/pii/S0972978X15000288 Image via: https://www.sciencedirect.com/science/article/abs/pii/S0972978X15000288