An alternative approach to SNP genotyping is haplo-typing.[5] Gene-based haplotypes are composed of the nucleotides that occur at SNP positions on a single chromosome at the locus of a single gene. Haplotypes are the most precise markers possible for a given gene because they contain all the variations in a gene. Hap-lotyping is a way of characterizing combinations of SNPs that might influence response and is considered to be a more accurate measure of phenotypic variation. However, SNP-based tests have greater power when the number of causative SNPs (a subset of the total set of SNPs) is smaller than the total number of haplotypes. One limitation of haplotyping is that haplotypes need to be determined for each individual, as SNPs detected from a pool of DNA from a number of individuals cannot yield haplotypes. Clinical trials using haplotyped individuals are the first genetically personalized medical treatments.

Table 1 Pharmacogenetic vs. pharmacogenomic studies




Focus of studies Scope of studies

Methods of study Relation to drugs Examination of drug effects

Application relevant to personalized medicine

Patient variability

Study of sequence variations in genes suspected of affecting drug response

SNP, expression profiles, and biochemistry

One drug and many genomes (patients)

Study of one drug in vivo in different patients with inherited gene variants

Patient/disease-specific healthcare

Drug variability

Studies encompass the whole genome

Expression profiling

Many drugs and one genome

Examination of differential effects of several compounds on gene expression in vivo or in vitro

Drug discovery and development or drug selection

Source: Modified and expanded from Ref. [2].

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Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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