ABSTRACT
A number of authors have suggested that the rise of the new genetics will allow for more accurate disease classification and better diagnosis of even common conditions. This chapter shows how genetic information leads to lumping and splitting in disease classification. It utilizes two example diseases which have undergone reclassification as a result of genetic information: Cystic Fibrosis (CF) and Diabetes. The availability of genetic tests changed the classification of CF; in Victor McKusik's terms, CF 'lumped' rather than 'split'. The boundaries of the classification expanded to include neighbouring conditions not generally regarded as CF. While the CF classification has expanded due to genetic explanation, diabetes has undergone 'splitting' into numerous sub-divisions. Andrew Cudworth constructs a classification system for diabetes which fixes the divisions between the two kinds of diabetes on genetic grounds, and provide the impetus for the splitting of diabetes into sub-diseases.
