ABSTRACT
Family-based designs are unique in that they use relatives to assess the genetic and
molecular epidemiology of disease. The number of relatives studied can range from two
family members to enormous pedigrees. The most commonly used studies are of familial
aggregation, twins, segregation, linkage, and association. The first three designs evaluate
the potential genetic basis of disease using patterns of coaggregation and do not require
the collection of biospecimens (e.g., DNA). In contrast, linkage and association studies
directly evaluate genetic markers-commonly searching across the entire human genome
for regions harboring potentially causal risk factors-and thus require the collection of
biospecimens on study subjects.
