The Hoxa3 gene is transcribed to yield mRNA (Manzanares et al. 1999, Manzanares et al. 2001, Diman et al. 2004, Su and Gudas 2008, Diman et al. 2011). Hoxa3 is expressed in rhombomere 5 and caudally through the central nervous system, ectoderm, and somitic mesoderm (Fainsod et al. 1987, Gaunt 1987).