Gene therapy to treat congenital blindness

October 28, 2009 by  
Filed under VISION

poor_eyesightMany people are born partially or fully blind. A recent development in biomedical research is bringing hope to people with congenital blindness and it’s called gene therapy.

Researchers at the University of Pennsylvania School of Medicine and the Center for Cellular and Molecular Therapeutics at The Children’s Hospital of Philadelphia used gene therapy to treat five children (age range: 8 to 17)and seven adults (maximum age of 44 years) born with Leber’s congenital amaurosis (LCA). All of the patients treated showed marked improvement in vision but the best improvements were seen among the children who, after the treatment were able to navigate a low-light obstacle course. Six of those treated are no longer classified as legally blind.

One of the patients, a 9-year old boy showed a “spectacular” recovery of vision after just 1 dose of gene therapy that allows him to play sports like other children.

About LCA:

Leber’s congenital amaurosis (LCA) is a group of inherited blinding diseases that damages light receptors in the retina. It usually begins stealing sight in early childhood and causes total blindness during a patient’s twenties or thirties. Currently, there is no treatment for LCA. LCA affects around 1 in 80,000 population.

About the therapy:

The therapy entails a single injection of genes that produce proteins to make light receptors in the retina. The researchers sued a vector to carry the genes. The research team used a vector, a genetically engineered adeno-associated virus, to carry a normal version of the gene, called RPE65, that is mutated in one form of LCA, called LCA2, that accounts for 8 to 16 percent of all LCA cases.

Effectiveness of the therapy was best seem among the children treated. Since LCA is a progressive disease which damages the retina, treatment is best when progression is stopped or delayed at a very early stage when retinal damage is still minimal.

According to principal author Dr. Albert M. Maguire

“Children who were treated with gene therapy are now able to walk and play just like any normally sighted child. They can also carry out classroom activities without visual aids.”

Gene therapy is relatively new development and is still in the experimental stage. The patients in the current study were among the first to receive gene therapy for a non-lethal disease. The children were the youngest so far to be treated with the therapy. The patients will be closely monitored in the coming years for signs of side effects or regression.

This new therapy gives hope to people with vision problems, not only those with LCA but other forms of retinal degeneration.

Genetics in heart disease treatment and diagnosis

September 24, 2008 by  
Filed under HEART AND STROKE

We are in the age of genomics. It is now possible to have our genome checked for predisposition to genetically-linked diseases such as cancer, Alzheimer’s, and yes – cardiovascular disease.

According to a review paper in 2005:

Genetic studies provide new insights into the pathogenesis of coronary artery disease and myocardial infarction. Future studies will focus on identification of new disease-causing genes and susceptibility genes, exploration of the molecular mechanisms by which mutations cause coronary artery disease/myocardiaI infarction, and gene-specific therapies for patients.”

It’s been three years. Are we ready yet for genetic-based treatment of heart disease? Let’s take a look at what the latest research on genetics say.

First gene therapy on trial

The first clinical trial of gene therapy for the treatment of heart failure was launched earlier this year.

Gene therapy is a technique for correcting defective genes responsible for disease development by inserting genes into a patient’s cells and tissues. In most gene therapy studies, a “normal” gene is inserted into the genome to replace an “abnormal” disease-causing gene.

In this therapy developed by researchers at the New York-Presbyterian Hospital and Columbia University Medical Center, the gene SERCA2a is injected into the patient with the hope that gene facilitates the replenishment of enzymes necessary for efficient heart pumping. In patients with heart failure, SERCA2a is depressed, leading to insufficient pumping of the heart and eventually heart failure.

Genetic fingerprinting for cardiomyopathy

Dilated cardiomyopathy is a condition where the heart is abnormally large so that the heart cavity is enlarged and stretched. This weakens the heart, making pumping inefficient and can eventually lead to heart failure. 36% of all cases of dilated cardiomyopathy is due to excessive alcohol consumption. However, distinction between alcohol-induced and non-alcohol induced cardiomyopathy is not an easy task. Because denial is one of the most common symptoms of alcoholism, self-reported evaluations are not reliable sources of data for prevention, diagnosis and control.

Researchers at the Boston University School of Medicine may just have found the answer. They report that they identified the “genomic ‘fingerprint’ for alcohol-induced heart failure.”

According to the authors,

now that we have this diagnostic marker or fingerprint, clinicians will be better able to monitor the progress of a patient who is being treated either medically or simply self reporting a cessation of drinking.”

Genetic markers for heart disease

In recent years, the search for genetic markers for human diseases has been stepped especially in the fields of oncology, neurodegenerative disorders, and cardiovascular medicine. Recent studies report about promising candidate genes that are strongly linked to the development of coronary heart disease and heart attack. However, these techniques are mainly experimental and still not part of standard clinical practices to diagnose and treat cardiovascular disorders.

How much more time do we need till we get there? It’s hard to say. It seems that medical science is making progress but progress is not that fast. Let’s touch base again in a couple of years.

Photo credit: DNA by clix at stock.xchng

What is Gene Therapy?

April 21, 2008 by  
Filed under CANCER

dna.jpg

Gene Therapy is an approach to treating diseases or genetic abnormalities at the genetic level. This therapy uses DNA as a medicine to treat disease.

Gene Therapy may involve replacing an abnormal or absent gene with a normal one, removing a malfunctioning gene or introducing a new gene to fight disease or for other reasons. This is considered an experimental therapy which is currently being conducted in clinical trials.

As defined by the American Society of Gene Therapy:

  • “It is an approach to treating disease by either modifying the expressions of an individual’s genes or correction of abnormal genes. By administration of DNA rather than a drug, many different diseases are currently being investigated as candidates for gene therapy. These include cystic fibrosis, cardiovascular disease, infectious diseases such as AIDS and cancer.”

While Gene Therapy is the replacement of DNA, Cell Therapy is a different type of therapy whose treatment replaces the entire cell (examples include bone marrow or blood transfusion). It’s obvious that often these two therapies will overlap.

Gene Therapy can be carried out at several levels.

  • Somatic Gene Therapy is the most common type of Gene Therapy targeting abnormal or absent genes which will result in treating a single patient and does not change hereditary genetics (genetics for the patient’s offspring).
  • Germline Gene Therapy occurs at the primary level of the egg and sperm. There is a potential to add or remove DNA which has an effect on hereditary diseases or simply changing the DNA for future generations. This is considered very controversial therapy.

The Center For Genetics Education provides a fact sheet on the ethics and safety of Gene Therapy.

Obviously, in order for Gene Therapy to be successful scientists must have the full understanding of human DNA.

What is the Human Genome Project?

First what is a genome?

A genome is a complete set of DNA, including all of the associated genes

The Human Genome Project’s task was to map the more than 3 million base DNA pairs.

This massive international initiative was supported by The U.S. Department of Energy, Office of Science and the National Institutes of Health. Information on the Human Genome Project is available at the website of The U.S. Department of Energy, Office of Science.

Gene Therapy in the treatment of cancer includes scientific studies into topics such as:

  • replacing altered genes with healthy genes
  • adding genes that will improve the immune system and fight cancer
  • inserting genes into cancer cells to make them more sensitive to chemotherapy or radiation
  • introducing genes that will destroy cancer cells

For more information on Gene Therapy and the treatment of cancer visit the National Cancer Institute site.

Resources and Information for current clinical trials in cancer gene therapy:

The Alliance for Cancer Gene Therapy

The National Cancer Institute

M.D. Anderson Cancer Center

Genetech Bio Oncology

Battling Books:

Gene Therapy For Cancer by Kelly K. Hunt, Stephan A. Vorburger, and Stephen G. Swisher (2007)

Long Term Prospects for Diabetes Patients

January 12, 2008 by  
Filed under DIABETES

The long term prospects for a person with diabetes are not set in stone. In many cases, they are a matter of choice.

There are many possible complications that come with diabetes.

Those taking insulin can experience a low glucose level. Hypoglycemia can lead to several ill effects. In extreme cases, coma is possible. At milder levels, muscle weakness or headache are common.

Diabetic acidosis may result from missing an insulin dose or as the result of infection or other cause. It can be life threatening. It’s most common in Type 1 diabetes, but may occur in those who suffer from Type 2 as well.

Insulin helps regulate blood glucose levels, but it also plays a role in burning body fat. When the insulin level drops drastically, the body starts burning fat, producing a characteristic ketone smell from the breath. The body tries to reduce the condition by inducing rapid breathing. But that strategy can only succeed to a certain degree.

Long term, diabetic retinopathy – a generation of the retina from damaged blood vessels – is another possibility. Kidney malfunction, as the kidneys come to filter less efficiently due to gradual destruction of the glomeruli, is also common.

But none of these conditions is inevitable, particularly today.

The possible long term effects of diabetes are very well known and there have been developed a number of strategies for dealing with them.

Accurate and careful self-care is the first line of defense. That keeps glucose and insulin levels where they should be, along with keeping the body fit to deal with the rigors of any problems that occur. It helps keep blood pressure in check to avoid long term complications from high blood pressure.

But there are longer term prospects on the horizon. Since diabetes is the result of lowered insulin production (Type 1) or inefficient use (Type 2) it can be adjusted by means other than drugs or diet. Note: there are other types of diabetes but these two cover over 95% of all chronic cases. Two of those are gene therapy or organ transplant.

Organ transplantation, in this case of a defective pancreas is an option for those who have Type 1 diabetes. Though a serious procedure, and not for everyone, the surgery has come a long way over the past 30 years, as has every other type of transplant. Immunosuppressive drugs are more effective to reduce the odds of rejection. Some gene therapy techniques are being developed to eliminate even the need for that.

Beyond being an adjunct in aiding immune system suppression, gene therapy can have a more direct role. Research is being conducted to correct autoimmune disorders, one type of which causes Type 1 diabetes. Even Type 2 diabetes sufferers have hope as well, though.

Gene therapy holds out the promise of being able to adjust the efficiency with which the body uses insulin, the characteristic of Type 2. Gene therapy may be able to affect the gene that controls the production of insulin beta cells.

Research is active and ongoing. There are good reasons to hope that in the years to come diabetes may be treated more effectively or even eliminated entirely.

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NOTE: The contents in this blog are for informational purposes only, and should not be construed as medical advice, diagnosis, treatment or a substitute for professional care. Always seek the advice of your physician or other qualified health professional before making changes to any existing treatment or program. Some of the information presented in this blog may already be out of date.