Biomedical Engineering Reference
In-Depth Information
Chapter 5
Molecular Diagnosis of Cardiovascular
Disorders
Introduction
Symptoms of cardiovascular diseases can often be confused with other pathologic
conditions and it is important that an accurate and expeditious diagnostic system is
available to help physicians make a rapid diagnosis. The classical methods of car-
diac diagnosis by auscultation, clinical acumen, and electrocardiography (ECG) are
now supplemented by echocardiography, cardiac molecular imaging, isotope scin-
tigraphy, and refined techniques of coronary catheterization, which can be com-
bined with therapeutic interventions. Biotechnology is also making important
contributions to cardiovascular diagnostics and some examples are given in this
chapter.
Basics of Molecular Diagnosis
Basic technologies of molecular diagnostics are the Southern blot, DNA probes,
pulsed field gel electrophoresis, and polymerase chain reaction (PCR). These tech-
nologies, their innovations, and non-PCR alternatives are described in detail in a
special report on molecular diagnostics (Jain
2011a
). PCR is a method of nucleic
acid analysis for producing large amounts of a specific DNA fragment of a defined
sequence and length from a small amount of a complex template. It can selectively
amplify a single molecule of DNA or RNA several millionfold in a few hours. Use
of this technology enables the detection and analysis of specific gene sequences in
a patient's sample without cloning. Analyses can be performed on even a few cells
from body fluids or in a drop of blood. Thus, PCR eliminates the need to prepare
large amounts of DNA from tissue samples. PCR has revolutionized molecular
diagnostics. Apart from laboratory diagnosis, it has affected genomics and biotech-
nology as well.
PCR is based on the enzymatic amplification of a fragment of DNA that is
flanked by two “primers” - short oligonucleotides that hybridize to the opposite
strands of the target sequence and then prime synthesis of the complementary DNA
sequence by DNA polymerase (an enzyme). The chain reaction is a three-step
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