Gene Therapy in Medicine

Somatic Gene Therapy

The insertion of a normally functioning gene into a patient to cure a genetic disorder

What happens in somatic gene therapy?

The DNA of somatic cells (body cells) are changed.

What is cystic fibrosis?

The genetic disorder where an individual produces too much mucus and it's hard to clear

1) What is somatic gene therapy in cystic fibrosis?

A harmless virus is genetically modified to carry a normal copy of the CFTR gene.

2) Somatic gene therapy in cystic fibrosis

The virus is dripped into the lungs through a thin tube inserted into the nose.

3) Somatic gene therapy in cystic fibrosis

Once inside the lungs, the virus enters the lung cells and delivers the healthy CFTR gene into the lung cell’s nucleus, where it becomes part of the cell’s DNA.

4) Somatic gene therapy in cystic fibrosis

As the lung cells divide, they carry the normal gene, allowing them to produce functional CFTR protein, helping to relieve symptoms of cystic fibrosis.

Advantages of Somatic Gene Therapy

• Targets specific tissues in need of treatment

• Extends life span

Disadvantages of Somatic Gene Therapy

• Cannot be passed to offspring

• Gene is introduced to a body cell (but not a reproductive cell)

• Only some cells get the functional gene

• It is temporary and needs repeating

What are germline cells?

Cells that eventually become sperm or eggs

Germ Line Cell Gene Therapy

A faulty allele is replaced with a functional allele in germ line cells or a very early embryo.

The effects of this are permanent and can be inherited.

Advantages of Germ Line Cell Gene Therapy

• Can be passed to offspring

• Gene is introduced to zygote

• All cells get functional allele

• Permanent

Disadvantages of Germ Line Cell Gene Therapy

• Cannot target a specific tissue

• Ethical implications

How does inserting a new gene into a chromosome affect the functioning of other genes in that chromosome?

• Frameshift

• Altered triplets

• Adjacent genes on the same chromosome switched on or off