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in the gene encoding the enzyme that metabolises the drug. Thus, it is possible to

analyse patient DNA prior to administration of a drug to determine what the likely

response will be. The technology to deduce a patient’s genotype is already developed

and indicated in Section 6.8.7. It is also now possible to analyse SNPs which may also

correlate with certain disease processes in a microarray type format. This opens up the

possibility that it may be possible to assign apharmacogeneticprofile at birth, in much

the same way as blood typing for later treatment. A further possibility is the determin-

ation of likely susceptibility to a disease based on genetic information. A number of

companies including the Icelandic genetics company deCode are able to provide

personal genetic information based on modelling and analysis of disease genes in large

population studies for certain conditions such as diabetes.

6.11 Molecular biotechnology and applications

It is a relatively short period of time since the early 1970s when the first recombinant

DNA experiments were carried out. However, huge strides have been made not only in

the development of molecular biology techniques but also in their practical applica-

tion. The molecular basis of disease and the new areas of genetic analysis and gene

therapy hold great promise. In the past medical science relied on the measurement

of protein and enzyme markers which reflected disease states. It is possible now not

only to detect such abnormalities at an earlier stage using mRNA techniques but also

in some cases to predict such states using genome analysis. The complete mapping

and sequencing of the human genome and the development of techniques such as

DNA microchips will certainly accelerate such events. Perhaps even more difficult is

Table 6.8General classification of oncogenes and their cellular
and biochemical functions

Oncogene Example Main details

G-proteins H-K- and N-ras GTP-binding protein/GTPase

Growth factors sis,nt-2,hst b-chain of platelet-derived growth factor (PDGF)

Growth factor receptors erbB Epidermal growth factor receptor (EGFR)

fms Colony-stimulating factor-1 receptor

Protein kinases abl,src Protein tyrosine kinases

mos,ras Protein serine kinases

Nucleus-located
transcription factors

mye DNA-binding protein

myb DNA-binding protein

jun,fos DNA-binding protein

260 Recombinant DNA and genetic analysis