[Issues on association studies on complex diseases].
Association study is widely used in elucidating genetic basis of complex diseases such as cardiovascular diseases, type 2 diabetes, essential hypertension and obesity. Some issues were discussed in the review, which include defining and controlling of confounding effects, selection of candidate genes and single nucleotide polymorphisms (SNPs), application of intermediate phenotype and haplotype analyses as well as judgement of the result in association studies. Population stratification is one of the major causes of confounding in association studies. It could be reduced by selecting relatives of affected patients as control, genome control and by using isolated populations which have higher homogeneity in genetic background. A candidate gene could be selected because of its' biological association with some disease or being congenerous to a known gene related to the disease. Appropriate application of intermediate phenotype of diseases and haplotype analyses may increase the opportunity to obtain meaningful findings in association studies. An optimal study design, sufficient sample size and proper controls, in conjunction of modern statistic analyses, association analyses would exert its effect on studies on susceptibility of human common diseases.
Yan
Wei-Li
WL
Division of Population Genetics and Prevention, Fu Wai Hospital, Chinese Academy of Medical Sciences, Beijing 100037, China. yanweili01@yahoo.com.cn
Gu
Dong-Feng
DF
D002318:Cardiovascular Diseases / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D006973:Hypertension / Q000235:genetics*; D009765:Obesity / Q000235:genetics*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide