10 Moreover, the influence of allelic variation in the 5′ region on regulation of OPRMf transcription was analyzed in a first study.11 Figure 2. Polymorphic spectrum of the 0PRM1 gene. The 6968 bp genomic reference sequence is presented as baseline; base pair coordinates

relative to the translation start site are given. Sequences are drawn to scale, which is indicated. All gene variants are specified … Figure 3. Site-directed mutagenesis of amino acid residues of OPRM1. A schematic representation of the putative seven transmembrane domain topology of the receptor is shown. Polymorphisms that affect protein sequence are indicated, and the mutations examined Inhibitors,research,lifescience,medical highlighted. … Multiple individually different forms of the human µ opiate receptor gene: Inhibitors,research,lifescience,medical relationship to gene function and phenotype The given sequence variability gives rise to numerous individually different forms of the OPRM1 gene. It is essential In diploid organisms to determine the specific combinations of given gene sequence variants for each of the chromosomes defined as haplotypes.

Because current experimental Inhibitors,research,lifescience,medical selleck inhibitor methods to determine the molecular haplotypes are still too labor- and cost-Intensive, statistical techniques were applied at this stage to predict these. In the group of African- American substance-dependent Individuals and controls, a total of 52 different haplotypes were distinguished (Figure 4A).9,12 These occurred at different frequencies in the population, as illustrated In Figure 4B. The five most frequent

haplotypes, nos 43, 14, 4, 24, and 7 were common Inhibitors,research,lifescience,medical to both substance-dependent Individuals and controls and constituted 66% to 73% of all haplotypes. An additional four of less frequent haplotypes were predicted, and a large number (43) of rare haplotypes occurring at frequencies <1% amounted to a total of 20% of all haplotypes. Thus, we will have to abandon Mendel's two-allele concept of a gene, which implicated existence of both a predominant “wild type” and various mutant forms. Figure 4. The human p opiate receptor study. A. The multiplicity of haplotypes. The polymorphic sites are specified Bay 11-7085 by Inhibitors,research,lifescience,medical positions 1-25, marked by an asterisk in Figure 2; 1, identical with the reference sequence; 2, different from the reference sequence. B. Distribution … The picture exemplified at the model of OPRM1 apparently applies, In view of our more extended candidate gene analyses, to at least one third of all genes studied.13 Allelic complexity In candidate genes may be large, and pose particular challenges to the analysis of genotype-phenotype relationships, particularly In the situation of complex traits. At first sight, such multiplicity of gene forms seems Irreconcilable with the assumption of dichotomous traits such as health and disease, or drug response and nonresponse. Moreover, the number of different haplotypes Is unfeaslbly large, so that the power Is not sufficient to detect an association with any single haplotype.