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SMN1 Gene Replacement

SMA is caused by mutation of the SMN1 gene. Researchers think that we may be able to treat SMA by replacing this faulty gene.

A type of treatment known as gene therapy, or gene transfer, is thought to be a viable option for restoring the SMN protein that is lacking in people with SMA. As well as replacing SMN1, gene transfer, targeting other important genes, could also be used to provide additional protection to motor neurons, the main cells affected by SMA.

How Gene Therapy Works

Gene therapy uses short pieces of DNA from genes, for example SMN1 for SMA. As it is not possible to insert the gene directly into a cell, scientists use a carrier called a vector to deliver the gene to the human cells that need it. For human gene therapy, harmless viruses are the vectors used to ‘infect’ the cells with the new DNA. Importantly, the viruses are modified so that they are not contagious and cannot cause disease.

Gene Therapy Challenges

The main cells affected by SMA, the lower motor neurons, are found in the spinal cord. This means vectors have to cross the blood-brain barrier in order to reach these target cells. The blood-brain-barrier is a semi-permeable covering that protects the brain from foreign substances and maintains a constant brain environment. Finding gene transfer techniques that can cross this barrier presents a real challenge.

Progress Highlights


AveXis to Imminently Initiate AVXS-101 Pivotal Trial in the US


AveXis announce results from AVXS-101 Phase I trial

New European Pivotal Study Announced by AveXis


New Pivotal Study announced by AveXis



Avexis Provides Update on Viral Gene Therapy Trial

Avexis Completes Phase I Trial Patient Enrolment


SMN Gene Therapy in a Large SMA Model         


Avexis Gene Therapy Gains Orphan Drug Status         

The importance of virus delivery route is discussed at the Cure SMA research conference 2014:

SMA Support UK at the Cure SMA Conference 2014     

Regenx reach deal with avexis to advance potential sma gene therapies

SMN1 gene therapy trial initiated in the US


SMN1 gene therapy known as scAAV9.CB.SMN receives Fast Track Status in the US   

Report from Azzouz Laboratory Gene Therapy for SMA                 


Separate published studies from the laboratories of Dr. Brian Kaspar, Dr. Martine Barkats, and Prof. Mimoun Azzouz show that the adeno-associated virus type 9 (AAV9) is able to cross the blood-brain barrier and produce SMN protein, resulting in drastic improvements in SMA model mice:

Gene Therapy Shows Promising Result for SMA