Introduction:


Gene therapy is a technique which can be used to treat many diseases and disorders of mankind. Gene therapy uses a technique of inserting a gene into a body cell or tissue of an individual who is suffering from an inherited disease or disorder. That is gene therapy aims to replace a defective mutated form of gene with a functional normal gene.

Neurological disorders were very difficult to treat because of the blood-brain barrier. However, due to some research activity in the field of gene therapy and genetics, scientists are hoping to discover the possibility of treating neurological diseases like Alzheimer's disease, epilepsy, Parkinson's disease by gene therapy.

Gene Therapy and Alzheimer's disease:

Scientists at the Salk Institute and the University of California, San Diego were able to treat mouse with AD by reducing the production of an enzyme known as β-secretase or BACE1 with the help of gene therapy. Enzyme as β-secretase or BACE1 degrade the APP and release the fragments which stick together to form plaques.

Method:

1. Scientists located the memory cells in the forebrain area, and injected the 40billion viral vectors via holes drilled in the area of upper skull.
2. Viral vectors invaded the memory cells and DNA was released into the nucleus of the cell.
3. The DNA released into the nucleus produced NGF (nerve growth factor).
4. NGF produced in these cells is then released into other cells of the brain, which play important role in memory.

Epilepsy:

Researchers at the Children's Hospital of Philadelphia were able to inhibit the onset of epilepsy in animals with brain insult. A brain insult is a initial stages of epilepsy.
Brain signal transduction was modified using gene therapy technique.
Gene therapy used successfully in rats to reduce the development of seizures.
A seizure is a condition caused by the rapid firing of brain cells, as a result of imbalance between the neurotransmitters and the glutamate system, and the neurotransmitter gamma-aminobutyric acid (GABA).

Method:

1. Researchers with the help of gene therapy modified the expression of α-1 subunit of GABA, by injecting the viral vector with the gene, to alter the protein expression in the brain.
2. Rats treated with gene therapy technique showed higher level of α-1 subunit of GABA protein, which helped in altering signal transduction in nerve cells, This technique can be used to prevent epilepsy in humans.

Gene Therapy and Parkinson's disease:

Parkinson's disease is neurological disorders where patients have shaking tremors are seen in the hands, muscular stiffness, difficulty in walking, and also balancing. Parkinson's disease is caused by the death of dopamine producing cells in the brain. Midbrain area known as substantia nigra, which helps in motor coordination is also affected in this condition.

Method:

1. Gene therapy using adeno-associated virus carrying dopamine coding gene was delivered into the brain region of patient with Parkinson's disease.
2. Patient's showed constant production of dopamine for around 1 year with no toxic side effects.

Scientists have also produced a gene based pharmaceutical compound known as Prosavin, for the treatment of patient with Parkinson's disease. Prosavin was effective in producing dopamine for a time period of 15 months and also showed no side effects.

Conclusion:

Researches in the field of genetic engineering, gene therapy and also human genetics are providing important information regarding the human genetic conditions or disorders. These findings can be used to treat the genetic condition with the help of new technique known as genetic engineering and this will also improve the patient's quality of life.

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