However, traditional linkage analyses lack power and precision when applied to complex disease. Association mapping, which compares the effects of different chromosomal variants, may be more successful at identifying genes of small effect. Association mapping can produce misleading results when the study population is not homogeneous, but includes individuals with different genetic backgrounds. QTDT can use all the information in a pedigree to construct powerful tests of association that are robust in the presence of stratification. Q stands for Quantitative.
Quantitative traits provide effective descriptions of many complex diseases, including asthma.
For many of these conditions, all or nothing definitions of disease are arbitrary and unsatisfactory. These pages are under construction.