26.5 Applications of Chimeraplasty:

• •  Gene Therapy for point mutations: Chimeraplasty has not been used in human subjects till date due to its unproven credibility and specificity, yet, it has a huge potential to correct genetic diseases like Sickle Cell and Crigler-Najjar Syndrome that occur due to a point mutation. Since, chimeraplasty can successfully alter maximum three consecutive base pairs in a gene hence it is a suitable candidate for treating diseases with point mutations.

•  Gene Therapy for autosomal dominant mutations: Another promising role of chimeraplasty can be correction of autosomal dominant mutations. Even one mutated gene in dominant mutation is enough to cause the disease because dominant gene expresses itself even in heterozygous condition thus the addition of a second normal gene by traditional gene therapy method is not capable of overcoming the expression of the defective gene. Chimeraplasty can be used effectively to correct the autosomal dominant defective gene itself.

•  "Knock out" genes: Chimeraplasty can be used to study the difference between the functional as well as the non-functional state of a gene. It would allow the knocking out of genes from adult tissues and enable designing and studying knock out strategies. Using chimeraplasty scientists can create knock out animal models for various human diseases.

26.6 Drawbacks of Chimeraplasty:

1. Using chimeraplasty only small corrections of maximum three consecutive base pairs in a gene can be performed.

2. One of the main problems faced with chimeraplasty is that the rate at which the gene correction takes place cannot be predicted or determined. Variation in gene correction between 1% and 40% has been reported and thus proves its unpredictable correction rate. The reason of such a variation remains unknown but may be linked to the improper delivery of chimera to the target DNA.

3. Another drawback of chimeraplasty is that the chimeric molecule may accidently act unspecifically causing alteration in other genes that are closely related to the target gene (due to sequence similarity of genes within a family) causing unwanted and harmful effects.

4. The RNA DNA hybrid is not robust enough and has been found to degrade within 48 hours.