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T R E AT M E N T

Advantages of genetic therapy

(A pro of gene therapy is that it doesn't cover up what's wrong but fixes the

'problem'.) (Ndsu.edu ) CF is a painful disease on the patient as well as their

families; it has a boundless social impact. The genetic treatment takes a long time to

work and is currently does not permanently solve the problem, but is helps cure it,

instead of treat it. All current treatments are meant to help ease the pain and make the disorder easier to live with. But genetic therapy is capable of creating a normal painless life for CF suffers. Also gene therapy is a rapidly growing research

industry reinforced by modern technology. When gene therapy is completely developed

it will prevent CF from killing its victims and might stop it from being inherited in

future generations.

Maryam HamoudaScience Grade 10 C

Genetics and Biotechnology

Limitation of genetic therapy

An obvious limitation of genetic therapy is that it still not developed. So far, the

normal gene vector is inserted randomly into the DNA causing many complications

in the phenotype of the body. This may harm or even kill the patient. Also germ line therapy is that it not only affects the sufferers, but also the generations after

them. The researchers still haven’t established the long-term affect of this

alteration in DNA in germ line therapy. It could create new disorders in future

generations. Finally, technology current isn’t adequate enough for gene therapy to treat many diseases. There are so many

conditions for gene therapy to be used on a patient. (All gene therapy at this stage is experimental and cannot be used for any disease.) (The UK Cystic Fibrosis Gene

Therapy Consortium)

The Problem

A mutation on the CFTR gene on chromosome 7 most commonly caused by a three-paired deletion stops salt from moving in a out of cells causing symptoms like poor digestions and severe coughing. If not treated, most CF patients will developed lung infections and are threatened by death before the age of 20. The thick mucus also blocks ducts in the pancreas and liver so digestive enzymes can't get into the intestines. (Without these enzymes, the intestines cannot properly digest food.) (PubMed Health) People who have this disorder often do not get the required nutrition and do not grow normally. Therefore, there is a treatment that solves this problem at its source; this solution is called Gene Therapy.

What is cystic fibrosis?

What causes Cystic Fibrosis?CF sufferers inherit a deficiency in a gene on chromosome 7 called CFTR (cystic fibrosis trans membrane conductance regulator). The

proper gene is in charge of producing proteins that assist salt (sodium chloride) enter and exit cells easily. When the gene doesn’t

work properly, the movement of salt is blocked and this creates thick tissues of mucus on the outside of the cells. The lung cells are the most severely affected cells by this blockage. (This mucus clogs

the airways in the lungs, and increases the risk of infection by bacteria.)  (Genetics Home Reference)

CF is a recessive disorder meaning that both parents must pass on the muted gene to their child. The infant must be homozygous for the defective CFTR gene on chromosome 7 to get the disease. If only one parent passes the gene to their child, then the child will not suffer CF, but will be a carrier of the defected gene. Carriers do not show any symptoms of the disease but can pass it down to their children.Chances of inheriting this disease vary depending on the parents’ genotypes. A child suffering CF can have two healthy parents, but they were both carriers and they passed this copy of the gene to him.

Genetic Treatment

The first type is called ‘Germ line gene therapy’. Germ line therapy would change the persons DNA by altering the original genes in

all the body cells. This not only affects the patient’s health but also future generations

wouldn’t inherit it through this person.

The other form of treatment is called ‘somatic gene therapy’. This form of treatment affects the body but does not change it. Somatic gene

therapy involves changing the defective gene in the individual but the change won't be inherited by the next generation. Somatic gene therapy is

the most popular and recommended since it doesn't have the ethical considerations like

germ line therapy.

The treatment will only work if the defective gene is replaced in all cells. To replace a

dysfunctional gene with a normal one, delivery vehicles called vectors containing the correct

gene are used. This vector is cut in a weakened adenovirus and filled with the normal gene. These viruses are originally responsible for

multiple respiratory illnesses, but when they are weakened they are harmless. These viruses are

then inserted into the cell to find its way to chromosome 7 where it should replace the

mutated gene. But first, the healthy gene will insert itself randomly in the DNA. This might be harmful or helpful to the patient depending where the gene is inserted, and this in random insertion might change a certain phenotype in the patient’s body. Further research must be

carried to find a way in which the gene can be inserted in the DNA without being harmful.

(Cystic fibrosis is an inherited disease characterized by the buildup of thick, sticky mucus that can damage many of the body's organs.)  (Nhs.uk) The symptoms of this disorder include gradual damage in the respiratory system

and persistent problems in the digestive system. The severity of the disease varies among various sufferers. Cystic fibroses was considered a lethal disease of childhood because suffers are born with it. Currently, developed

biotechnology treatments help manage the disease affectively and expand the lifespan of cystic fibrosis patients till adulthood.

Genetic Treatment

Gene therapy is a treatment currently in clinical trials, in which the healthy CFTR gene is

inserted into the lung cells of a patient to correct the defective gene. It offers the most effective solution because it tackles the root cause of CF rather than just treating the symptoms. Since all the cells in the body carry the same faulty gene, the sticky mucus builds on all organs. By adding

copies of the normal gene into the body the correct protein will be produced as well as the defective one. The mutated gene will not stop the normal one form working, so inserting the

gene in the affected areas would fix the problem in the affected tissue. Treating the lungs

genetically is feasible through an inhaler, which delivers the proper CFTR gene into the lung

tissues.

Gene therapy identifies the defective gene and to corrects it by replacing it with the normal gene. There are two types of gene therapy that are still

being developed by researchers and haven’t been used on humans.