EVALUATION OF NATURE-NURTURE IMPACT ON REPRODUCTIVE HEALTH USING HALF-SIBLINGS

Research in the field of preventive medicine will increasingly focus o n the role of genetic susceptibility in disease etiology. Epidemiology plays an important role in identifying which diseases are good candid ates for such research activity. Computerized population registries of unstable partner relationships and change in environmental exposure s ettings may provide new tools for research. We illustrate these tools using facial cleft defects as an example. The design is based upon com puterized and stored data from large population samples. Data on chang e of partner or environment between births are used to learn about the recurrence risks for diseases that were present in the first child. T he study focused on a susceptible subgroup of the population who previ ously had had an affected child. Thus, by definition, these couples ha d a sufficient set of causes to initiate the disease and an increased risk of recurrence if relevant genetic or environmental factors remain ed unchanged. When considering recurrence risks after changes in possi ble genetic or nongenetic risk factors, etiologically important clues may emerge. The example confirms that genetic factors play a major rol e in facial cleft defects.