SALL4 and Okihiro syndrome: SALL4 is a transcription factor (TF) involved in limb development; in humans, loss-of-function mutations in SALL4 cause Duane-radial ray syndrome (Kohlhase et al., 2002), an autosomal recessive condition characterized by limb anomalies, similar to the ones observed in TE (Kohlhase et al., 2003).