Teratology, Dysmorphology, Genetics (continued)

The Teratology Society defines Teratology as the study of serious deviations of normal development, birth defects* (structural, functional, and physiological), and inclusive of: 

  • Genetic Influences
  • Drugs and Birth Defects
  • Maternal health and nutrition Influences
  • Environmental Exposures and Birth Defects
  • Developmental and Reproductive Toxicology  **

Teratology Principles (please see).

Dysmorphology concerns “differences of body structure” – isolated or multiple, observed in normal individuals or associated with congenital disorders of genetic or environmental nature,  and formulation of specific nomenclature inclusive of characteristic clusters of signs as a signal of recognizable syndromes. A further excellent description is found in the Smith’s Recognizable Patterns of Human Malformation. ***

* “Birth Defect” is a popular vernacular substitute for “malformations” – both terms need clarifications: they apply to functional and structural anomalies of both genetic and environmental nature.
** Reproductive “Toxicology” wrongly implies equating a toxin with a teratogen or presumes that Teratology is a sub-set of Toxicology (see principles of Teratology).
*** In the introduction “Dysmorphology Approach and Classification” to the “Smith’s Recognizable Patterns of Human Malformations” (see next page), the following salient points are underscored; “… devoted to patterns of malformation … accurate diagnosis of a specific syndrome … a prerequisite for (care and prevention) … family history is an essential … interpretation of anomalies from the viewpoint of developmental anatomy … which anomaly represents the earliest defect in morphogenesis? … can all anomalies be explained on the basis of a single problem in morphogenesis? … malformation sequence? … deformation sequence? … disruption sequence? … malformation syndromes? … a defect may be a feature in several syndromes of variant etiology … diagnosis can be rendered on the basis of a total pattern of anomalies … intra and inter individual variability in expression  … similar phenotypes (heterogeneity of physical similarities) …