Embryology and Classification of Congenital Upper Limb Anomalies

Understanding the etiologies underlying congenital limb anomalies is an important step in developing corrective or preventative therapies. To accomplish this task, knowledge of how the limb develops is crucial. The position of limb outgrowth is under precise molecular control. In addition, the subsequent growth and differentiation of the limb are tightly regulated by a complex network of signaling molecules secreted by specialized zones in the limb, known as signaling centers. Any disruption in the regulation of these molecules can cause dysmorphogenesis or dysplasias that result in congenital limb anomalies. This chapter will review recent insights from developmental biology, clinical genetics, and hand surgery that define our current understanding of how limb anomalies occur.