Heart transplantation, i.e. replacement of a failing heart with a heart from a suitable donor, continues to be the "gold standard" treatment for end-stage heart failure. The procedure's success rate has so improved today that patients are living 20 years or more post-surgery.
One of the most important complications of heart transplantation is the rejection of a foreign graft. For such a complicated and expensive procedure as a heart transplant, it is vital, hence, to make sure that chances of rejection are low. This is the scenario where Gene expression profiling test scores attain importance.
AdvertisementThe test score can be used to identify transplant recipients who have a low probability of rejection. The Invasive Monitoring Attenuation through Gene Expressioná(IMAGE) trial dived deep into the utility of gene expression profiling.
Gene expression profiling is a technique used in the field of molecular biology to measure the expression of thousands of genes simultaneously. It is known that each and every cell in our body contain the genome, i.e. the entire hereditary information. However, not all the genes express at a given time; only a subset is expressed. The term 'expression' refers to the way genes are transcribed to functional products called proteins. Genetic information is conveyed from DNA to the ribosome via messenger RNA (mRNA).
Commonly used techniques of gene expression profiling include:
* DNA microarray technology
* Serial Analysis of Gene Expression (SAGE)
DNA microarray technology employs pre-defined DNA sequences known as probes. These probes are contained in microscopic DNA spots attached to a solid surface. A DNA microarray (also called gene chip, DNA chip, or biochip) is a collection of such microscopic DNA spots attached to a solid surface. Serial Analysis of Gene Expression (SAGE) is different from microarray technology in that it does not require prior knowledge of the genetic sequences to be analysed.
The IMAGE study finds that the variability of a heart recipient's gene expression profiling test scores over time may help to assess the prognosis of the patient following transplantation. It may predict the probability of a transplanted heart getting rejected by the recipient's body.
1. Deng MC et al; for the IMAGE Study Group; Utility of Gene Expression Profiling Score Variability to Predict Clinical Events in Heart Transplant Recipients; Transplantation 2014
2. The Annals of Thoracic Surgery.