Page 56 - Clinical Biochemistry

Loop Mediated amplification is particularly robust and in diagnostic development for HBV
and HCV POC assays.

Detection of Genetic Mutations

To detect rare genetic mutations leading to cancer. Another example, boys afflicted with
Duchenne muscular dystrophy have deletions in the protein coding regions (exons) of the
dystrophin gene. The gene's great size makes it impractical to examine its entire length for
mutations, so a technique called "multiplex PCR" is used to sample various regions of the gene
from one end to the other.
• The technique involves simultaneous amplification from nine different sets of primers, all
within the same test tube.
• Each set of primers is chosen to produce a different-sized amplification product from a
different region of the dystrophin gene.
• Following amplification, the PCR products are analyzed by gel electrophoresis. Boys having
a normal dystrophin gene will display nine different-sized amplification products, while boys
with deletions in the gene will be missing one or more of the PCR products.

In forensic investigations
PCR is helpful (when only a very small amount of the DNA is available), e.g. a drop blood,
sperm or a single hair.

Evolutionary studies

Minute quantities of DNA are isolated from the available biological sample, amplified and
sequenced.

Identification of genetic defect in the fetus

DNA isolated from cells in the amniotic fluid of pregnant women. The DNA then can be
analyzed for the presence of a genetic defect in the fetus.

Can be a test for the future and past diseases
• Research is expected eventually to yield predictive tests: With PCR analysis of cells shed
into feces, for example, doctors have already demonstrated premalignant changes in the
gastrointestinal tract, such as mutations in genes that protect against tumors.