Conditional gene knockout is a relatively new technique, an offshoot of gene knockout technology with the exception that a specific target gene is eliminated from a single organ in the body rather than the whole body as gene knockout technology would entail. Thus this allows for more sophisticated experiments than traditional gene knockout studies and hence more useful and practical in its approach. There are several advantages conferred by this technique over the conventional type in that such genetically modified mice are not only able to survive longer but also, the technique overall is more clean and scientifically precise. The most commonly used technique for conditional gene knockout is the Cre-Lox recombination system. Cre recombinase is known to be expressed in only a few target cell types and hence the researcher would be typically able to decide where exactly the gene in question is to be knocked out thus allowing for a greater degree of freedom and scientific accuracy.
A team of researchers from UT Southwestern Medical Center have successfully knocked out a specific gene in mouse brain thought to be involved in the onset of Alzheimer's disease which codes for the enzyme cyclin-dependent kinase 5 (Cdk5). Such genetically-engineered mice were found to be 'smarter' than normal mice and were able to handle complex tasks more intelligently compared to 'normal' mice bred in the laboratory.[1]