Introduction to genetics

In this chapter, we provide an overview of the field of human genetics addressing the key molecular approaches in the study of the role of familial factors and genetic determinants in the causation of complex diseases such as cardiovascular disease, Asthma, and diabetes. The genetic complexity of multigenic disorders is outlined underpinning the important need of understanding the linkage disequilibrium (LD) structure of the human genome, ethnic and sex-related differences, and the need for applying approaches that allow for gene–gene and gene–environment interaction studies. While traditional linkage and association studies have been highly successful in uncovering variants that underlie monogenetic disorders and delivered some success in the field of multigenic disorders, the sequencing of the human genome and, more recently, the completion of the International HapMap Project mark the start of a new phase in human genetics. The HapMap project provides an unprecedented resource to investigators by characterizing the patterns of genetic variation and LD structure across four geographical populations, facilitating the design of genome-wide (GW) associationstudies and unveiling some of the complexity of human genetic diversity. The rapid development in new technology platforms in recent years is now enabling investigators to conduct high-throughput experiments scanning through the whole genome in search for genes and variants that underlie many of the common diseases that affect human beings.