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.
the most important complications of heart
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.
test score can be used to identify transplant recipients who have a low
probability of rejection. The Invasive
Monitoring Attenuation through Gene
Expression (IMAGE) trial dived
deep into the utility of gene expression
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
the ribosome via messenger RNA (mRNA).
used techniques of gene expression profiling include:
* DNA microarray
* Serial Analysis of Gene Expression (SAGE)
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.
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.
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
Annals of Thoracic Surgery