Gene therapy

What is gene therapy ?

Altering a persons genetic material often to treat a disease

How can we use gene therapy to treat a disease ?

we insert a functional allele into cells that have faulty alleles and this allele gets expressed, stopping symptoms of the disease being caused by the faulty alleles

This is not passed to offspring because it isn’t permanently altering the genome

What is somatic gene therapy

Certain disorders are due to the inheritance of 2 faulty recessive alleles such as cystic fibrosis which mean the cells lack the protein that should be being produced.

What is the method (lip)for somatic gene therapy ?

Functional alleles are packed into a liposome

The liposomes are delivered via an inhaler

Some liposomes pass through the plasma membrane of cells lining the respiratory tract

If they are able to pass through the nuclear envelope the functional alleles can be inserted into the genome and the protein gets expressed due to the now functional alleles replacing the faulty ones

What is another method for somatic cell gene therapy ?

use viruses that naturally infect humans as they are used to inserting their genome. They must be genetically modified to no longer be able to cause that disease and also to encase the functioning allele

What is a problem with the viral method of somatic cell gene therapy ?

the immune system may still respond to the virus leading to not only unsuccessful genome insertion, but also a developed immunity to the virus so future deliveries may be problematic :

E.g allele in the wrong genome location

Eg in genes interrupting in the regulation of cell division which could lead to cancer

Or could cause a frame shift leading to altered triplets and possible non functioning proteins further on

What is germ line therapy ?

Inserting functional alleles into a gamete or a zygote

This leads to permanent genome change and offspring will also have this altered gene which is why it is illegal in humans because they cannot consent to

There is also a possible link with gene insertion and cancer