The following two articles in this issue of the Journal by Opitz and Neri [2013] and Hennekam et al. [2013] address complex issues surrounding the definitions and terminology for congenital anomalies. Opitz and Neri [2013] provide an historical foundation and Hennekam et al. [2013] add the newest addition to the Elements of Morphology by proposing consensus definitions for the commonly used general terms. Like the other papers in this series [Allanson et al., 2009], these two articles will be free access and included on the National Institutes of Health web page for the Elements of Morphology project [].

Taking up where three international working groups on malformation nomenclature left off in the 1980s, the Elements Working Group proposes standard terminology and definitions for general terms in the field, including anomaly, malformation, deformation, sequence, and syndrome. The process of developing these consensus definitions was time consuming and stringent. The methodology was described in the original introduction to the Elements series in 2009 [Allanson et al., 2009].

Consensus definitions for the commonly used terms of morphology have been proposed by three different international groups before this current work:

  1. In 1975, a group of clinical geneticists including Doctors David W. Smith, John M. Opitz, Robert J. Gorlin, and M. Michael Cohen Jr., met at the NIH to discuss suggestions for classification and nomenclature.
  2. The second meeting was chaired by Dr. Jürgen Spranger and also included Doctors Opitz, Smith and Judith Hall. A widely cited and seminal paper emerged from that meeting [Spranger et al., 1982].
  3. A third international working group convened in Berlin in 1987 and the definitions of certain terms including syndromes were revised and updated. I have provided a summary of these three meetings in the past [Carey, 2011]. The purpose of the recent Elements contribution was to provide a current analysis and rethinking of the terms proposed in the 1980s; the need for such revisions is obvious given recent advances in knowledge regarding the molecular basis of congenital defects.

As in the original Elements of Morphology series in 2009, the consensus terminology and definitions are the final product of a unique peer-review process: After the authors of this paper developed the original definitions over the course of 3 months and met at the NIH to refine the terms, the proposed definitions were submitted to the original Elements of Morphology Working Group and other clinical geneticists. Those that provided input and critique of the definitions are included in the paper's Appendix.

The American Journal of Medical Genetics is pleased to publish the latest editions to the Elements of Morphology project, and these will be available on the Journal's web page at


  1. Top of page
  • Allanson JE, Biesecker LG, Hennekam RCM. 2009. The elements of morphology: Introduction. Am J Med Genet Part A 149A:25.
  • Carey JC. 2011. The clinical delineation of malformation syndromes: Historical prospective and future direction. Am J Med Genet Part A 155A:20662068.
  • Hennekam RCM, Biesecker LG, Allanson JE, Hall JG, Opitz JM, Temple IK, Carey JC, Elements of Morphology Consortium. 2013. Elements of morphology: General terms for congenital anomalies. Am J Med Genet Part A 161A, this issue.
  • Opitz JM, Neri G. 2013. Historical perspective on developmental concepts and terminology. Am J Med Genet Part A 161A, this issue.
  • Spranger J, Benirschke K, Hall JG, Lenz W, Lowry RB, Opitz JM, Pinsky L, Schwarzacher HG, Smith DW. 1982. Errors of morphogenesis: concepts and terms; recommendations of an international working group. J Pediatr 100:160165.