Genetic markers to predict polygenic disease.

Many genetic markers that relate to common multifactorial disease in adults have been identified during the past 15 years. Their use as adjuncts for the diagnosis, prognosis, prediction of disease or targeting therapy for these disorders has commenced; good examples being the Factor V Leiden mutation for venous-thromboembolism, lipoprotein lipase mutations for hypertriglyceridemia and the apolipoprotein E4 variant for Alzheimer's dementia. However, extensive gene-gene interactions and gene-environment interactions make their use more complex than markers for the simpler monogenic disorders (eg, cystic fibrosis, or Duchennne's muscular dystrophy). Possible misapplications of the use of genetic markers for multifactorial disease are discussed.