Association studies, allelic

Daniels J, Flolmans P, Williams N et al 1998b A simple method for analyzing microsatellite allele image patterns generated from DNA pools and its application to allelic association studies. Am J Flum Genet 62 1189—1197... 

Ho, G.T., Soranzo, N., Tate, S.K., Drummond, H., Nimmo, E.R., Tenesa, A., Arnott, I.D. and Satsangi, J. (2006) Lack of association of the pregnane X receptor (PXR/NR1I2) gene with inflammatory bowel disease parallel allelic association study and... 

Studies have led to the identification of 14 alleles associated with PFK deficiency. Eight missense mutations, one nonsense mutation, one frameshift muta-... 

Association studies are used to identify common alleles more frequently associated with phenotypic traits such as drug response or ADRs. These associated alleles are called causal polymorphisms or functional polymorphisms and are risk-conferring factors of the trait at the population level, while, at the individual level, they impact either on the cellular level of the gene product or its function. 

Many statistical methods have been developed for association studies [52, 53] that mostly consist of testing each polymorphism separately with the disease. It has been shown that the power of such methods decreases rapidly when the markers are in low or even moderate LD with the risk-conferring polymorphism [54]. One way to overcome this defect is to use haplotype-based tests [47, 55, 56] that combine different alleles of different markers. Haplotypes are likely to capture... 

In addition, haplotype-based methods can increase the power of association studies since the allelic architecture of the risk factor is unknown. Recent examples of association studies suggest that haplotypes can be the responsible factors [58]. The Apo E4 allele , which is associated with Alzheimer s disease, is a possible example since it results from the substitution of two of non-conservative polymorphisms encoding for residues 112 and 158 [59]. 

Association studies have proven to be more fruitful. In such studies, the allelic frequencies for specific marker genes are compared with a control population. When OCD patients were investigated for the association of tics with the dopamine receptor 2 marker it was shown that there was an increased frequency of homozygosity for the allele A2 of TaqIA at the D2 receptor locus. Not all investigators could replicate this finding however. No positive associations have been found between OCD and the D3 gene while there was some association found between OCD with tics and the D4... 

ASSOCIATION STUDIES OF DOPAMINE-RELATED ALLELES IN NEUROPSYCHIATRIC DISORDERS... 

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