Dr Ira Shah
Consultant Pediatrician, Nanavati Hospital and B.J.Wadia Hospital for Children, Mumbai
Editor - Pediatric Oncall

What is gene therapy?
In patients with genetic disorders due to mutation in a gene, the defective gene leads to a disease. With gene therapy the correct genes are infused inside the body or into patient?s stem cells in the laboratory by piggybacking them on a non-functional virus. Once the genes are inserted into the cells, these cells are infused into the patients to restore the genetic defect.

Why are viruses required to pass on correct gene in gene therapy?
Since genes cannot be inserted directly into the cells, viruses can carry the genes as viruses can enter into cells without a problem. These viruses are modified such that they cannot cause disease but only transmit the correct gene into the cell.

Why stem cells are used for inserting genes in gene therapy?
Stem cells are primitive cells and can give rise to various types of cells in the body. Thus correcting the genetic defect in stem cells can lead to correction in various cells of the body and this effect is lifelong.

Which kind of genetic disorders have been treated with gene therapy?
Not every type of genetic disorder can be treated with gene therapy. Very few patients with Severe Combined Immunodeficiency-SCID (a serious, rare primary immunodeficiency) have been treated with gene therapy. Around 20 babies with SCID have been treated but 3 children have developed an unusual kind of blood cancer. Thus gene therapy is currently in an experimental phase and not routinely recommended. Trials of gene therapy are also going on for chronic granulomatous disease (CGD).

Last updated on 26-3-2011