In particular, we excluded a HDAC4 deletion (2q37.3 deletion syndrome), a STX16 deletion (PHP1b), a mutation in PRKAR1A, PDE3A, or PDE4D (acrodysostosis), a mutation in PTH1R (Blomstrand or Eiken dysplasia), or a mutation in other syndromic causal genes or in genes coding for other intracellular signal transmission effectors. The gene discussed is PDE4D; the disease is acrodysostosis.