PRIMARY DEVELOPMENTAL FIELD .3. CLINICAL AND EPIDEMIOLOGIC-STUDY OF BLASTOGENETIC ANOMALIES AND THEIR RELATIONSHIP TO DIFFERENT MCA PATTERNS

Opitz [1993: BD:OAS XXIX (1):3-37] suggested that during blastogenesis the entire embryo constitutes a developmental field, i.e., the primar y developmental field, Based on this principle, he postulated that a s ingle ''hit,'' that during late morphogenesis would cause a monotopic malformation, during blastogenesis would produce a polytopic malformat ion or an association, Lubinsky [1986: Am J Med Genet [Supp1]2:6-16] h ad stated previously that ''since the embryo develops in an integrated manner, organized and differentiating spatially, temporally. and in a n epimorphically hierarchical manner, disturbances result in nonrandom patterns of anomalies.'' He then concluded that ''associations are de rivatives of causally nonspecific disruptive events acting on developm ental fields.'' These concepts, confirmed by our epidemiological obser vations [Martinez-Frias, 1994: Am J Med Genet 49:45-51], imply that so me associations are, by definition, abnormalities of blastogenesis tha t is, that their component congenital anomalies are produced by events occurring during the first 4 weeks of development, We present an anal ysis of the characteristics of blastogenetic anom-alies and their rela tionship with midline abnormalities, as well as with the schisis and V ACTERL associations. (C) 1997 Wiley-Liss, Inc.