Dr. Di Renzios group aims to characterize the amount and patterns of genetic variation in human populations, and to elucidate the forces that shape and maintain this variation. Forces such as demographic change or population structure exert genome-wide effects, while others such as natural selection result in locus-specific effects. As greater attention is focused on dissecting the genetic bases of common diseases, an understanding of the patterns of human sequence variation is recognized as a critical step toward improved approaches to disease mapping.

Dr. Di Renzios work takes advantage of the proliferation of new genetic tools for population studies, to test increasingly complex and, thus, more realistic scenarios of population history. In one ongoing project, Dr. Di Renzio is surveying sequence variation and linkage disequilibrium in a number of independent regions of the human genome and in ethnically diverse populations. This project is generating important information for the design of disease association studies.

Dr. Di Renzio is also studying the evolution of a polymorphic variant contributing to type 2 diabetes susceptibility. An attractive hypothesis, called the "thrifty genotype" hypothesis, proposes that diabetes variants have evolved under the effect of positive natural selection. Because natural selection leaves a distinctive signature on the amount and pattern of sequence variation and linkage disequilibrium in the region linked to the selected site, she has designed a survey to detect this. It involves quantitative comparison of both sequence and haplotype variation, and the degree and pattern of inter-population differentiation, at this site versus that at neutrally evolving loci. In addition, Dr. Di Renzio will investigate the degree and pattern of inter-population differentiation at this site and ask whether it differs from those observed at other neutrally evolving loci in the human genome.