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Limits of genetic testing

Genetic tests are not available for every possible inherited disorder, and are not completely reliable. They may produce false positive or false negative results, which can have serious consequences for the parents involved.

False positives

A false positive is a genetic test that wrongly detected a certain allele or faulty chromosome. The individual could believe something is wrong, when it is actually fine.

False negatives

A false negative is a genetic test has failed to detect a certain allele or faulty chromosome. The parents may be wrongly reassured. These results can have a major impact on the lives of individuals, through pregnancy termination, future decisions and planning the level of care needed for children with inherited disorders.

Gene therapy

Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries a faulty allele. It is not always successful, and research is continuing to try and develop this possible treatment further.

Gene therapy involves these basic steps:

1. identify the gene involved in the genetic disorder
2. restriction enzymes cut out the normal allele
3. many copies of the allele are made
4. copies of the normal working allele are put into the cells of a person who has the genetic disorder due to a mutated or faulty copy of an allele

Problems in the process

The problems involved in the process:

• the alleles may not go into every target cell, which are cells that need the new non-faulty cell
• the alleles may be inserted into the chromosomes in random places, rather than in the required position, so they do not work properly
• some treated cells may be replaced naturally by the patient's own untreated cells, as cells are frequently replaced through the process of mitosis during growth and repair

Different methods

Different methods are used to get the alleles into the patient's cells, including:

• using nose sprays, which allow a patient to introduce the working allele up their nose and it will be taken into their body and incorporated
• using cold viruses that are modified to carry the allele - the viruses go into the cells and infect them
• the direct injection of DNA

Gene therapy can have major ethical implications in society as people disagree with gene alteration in people, as they believe it is unnatural.

Other people think that gene therapy is a good idea, as it prevents unnecessary suffering in affected individuals. Gene therapy only affects the individual involved in the process and not any future generations who would be likely to inherit similar diseases.