A BRIEF SURVEY of the vast subject of "Genetics and Human Congenital Malformations" can scarcely be expected to be systematic. Accordingly, discussion of the subject will be limited to a series of more or less unrelated observations concerning genetics and the study of human teratology. The first portion of this discussion will be devoted to three general points concerning which there seems to be room for misunderstanding between the genetically and nongenetically oriented student of teratology. The latter portion of the discussion will be concerned with drawing attention to some general genetic approaches which may be profitable in specific areas. In approaching the material in this fashion, familiarity with the current status of work on human teratology is assumed. It is further assumed that the principal reason for this Conference on Teratology is to consider useful lines of attack on outstanding problems in this area.It is important at the outset to establish the fact that, from the genetic point of view, human malformations are a very "mixed bag" indeed. At the one extreme there are malformations which have a clear-cut and relatively simple genetic basis. Many of the skeletal malformations, such as the relatively benign brachydactyly or polydactyly, or the more serious ectrodactyly (split hand) or acheiropodia, fall into this category. At the other extreme there are a few malformations, such as tracheo-esophageal fistula1 which thus far have not been demonstrated to show a noteworthy tendency to concentrate in particular families. The majority of congenital malformations fall into neither of these extremes, showing clearly statistical tendencies to occur in certain families, but in these tendencies not following any simple pattern.
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