The developmental field concept in pediatric pathology--especially with respect to fibular a/hypoplasia and the DiGeorge anomaly.

Identical anomalies produced by different causes such as aneuploidy, gene mutation, teratogenic chemicals, and certain surgical procedures are a clear indication that embryonic primordia respond as units in the production of developmental anomalies of anatomic structure. Hence, they must also act as units during normal ontogeny. The presence of identical malformations in different mammalian species identifies developmental and anatomic homology by virtue of descent from a common ancestor. These dys- and orthomorphogenetically reactive units are the equivalents of the classic experimental embryologist's epimorphic fields, which are those units of the embryo in which the development of complex structures appropriate to the species is determined and controlled in a spatially coordinated, temporarily synchronous, and epimorphically hierarchical manner that expresses both species-nonspecific (that is, phylogenetic) and species-specific genetically coded developmental information. Thus, it is as important for pathologists as it is for clinical geneticists to steep themselves in the art and science of phenotype analysis and to be able to do all of those studies, including anthropometry, dermatoglyphics, and growth analysis, that are required to arrive at inferences of cause and pathogenesis from the phenotype. There is probably one other incentive besides the ethical and intellectual ones to do this and to do it as well as possible, namely, the medico-legal consequences. If pathologists fail to illuminate the causal genesis of a given case to aid in preventing recurrence, then, in short order, they might be held equally as liable as clinicians for missing high recurrence risk genetic diagnoses. These depressing considerations aside, it is important to close on a positive note. As at the outset, we want to emphasize once more that, without question, this is the most exciting time to be working in the field of developmental pathology. In this specialty a marriage is occurring of several types of investigational methods, ranging from humble morphologic studies to metabolic analysis to the most sophisticated designs of molecular biology, to produce new interdisciplinary approaches to the solution of the oldest intellectual problem confronting medicine--how does the "fabric of the human body" (in the immortal words of Vesalius) come about?(ABSTRACT TRUNCATED AT 250 WORDS)