Gene Therapy Tayte Kozlowski

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How diseases are chosen for gene therapy

The condition be able to be corrected by adding one or a few functional genes

single gene mutations are better candidates than multi factorial

How the gene factors into the disorder?

by knowing which tissues the disorder affects, what role the protein encoded by the gene plays within the cells of that tissue, and exactly how mutations in the gene affect the protein's function, how to go about treating the disorder can be determined

DNA copy of the gene must be available in laboratory.

it is necessary to know which genes will be pursued before treatment

Genetically modifying immune cells to target specific molecules

isolates immune cells and genetically engineers them to recognize a specific antigen.

When returned to the patient, modified cells will find and destroy any cells that carry antigen/product

Gene Silencing

approach used to turn a gene "off" so that no protein is made from it.

Repairing Mutations

aimed at replacing a defective copy of a gene with a working copy

Viral vectors repair mutations directly in DNA. This tech. uses enzymes target DNA and cut out the faulty sequence and replace with a functional copy.

"Spliceosome-Mediated RNA Trans-splicing" targets and repairs the messenger RNA copied from mutated gene. This technique repairs section of the mRNA rather than entire gene

Types of Mutations Where Adding a Working Copy Won't Work

Dominant negative

This mutation leads to production of a dominant-negative protein that may block a normal protein from doing its job

Gain-of-function

A gain-of-function mutation makes a protein that acts abnormally, causing problems all on its own (Cancer)

Improper regulation

Problems of gene regulation

Protein is functioning as it should, but there's a problem with where, when, or how much protein is being made.

Non-viral Vectors

Can overcome limitations of viral

generally ex-vivo

less effective

Viral Vectors

Drawbacks of viral vectors: -carry a limited amount of genetic material -can cause immune responses in patients (patients may get sick or immune system may block the virus from delivering the gene to the patient's cells)

Advantages of viral vectors: -good at targeting and entering cells -can be modified so that they can't replicate and destroy cells

2.1.1 Gene Therapy

Gene Delivery: Tools of the Trade

ex vivo is to deliver the gene to cells that have been removed from the body and are growing in culture

in vivo is to inject the vector directly into the patient

vectors must: TARGET the right cells, INTEGRATE the gene, ACTIVATE the gene, and AVOID harmful side effects

vectors are customized to address unique features of disorders

vectors are DNA delivery vehicles

What is Gene Therapy?

single gene genetic disorders are better candidates than multifactorial

cell builds RNA and protein molecules from correct gene

uses a vector (typically a virus) to deliver a gene to the cells

the transplantation of normal genes in place of missing or defective ones to correct genetic disorders

Approaches to Gene Therapy

sometimes just adding a working copy of the gene won't solve the problem