On lumpers and splitters, or the nosology of genetic disease.

As Knut Faber pointed out in his Nosography,l mendelism contributed much to nosology by focusing attention on specific entities. Bacteriology, with its similar emphasis on specific etiology and specific entities, had a comparable effect. One need only recall that a century ago, symptoms such as jaundice, dropsy and anemia were viewed as entities, in much of medicine at least, to realize the nosologic contributions of mendelism and bacteriology. But the main object here is to review some contemporary problems in the nosology of genetic disease.