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cancer is one of the most common malignancies in women. In breast cancer
treatment and preven, people who posses a family history of breast cancer are
recommended to experience genetic test for early diagnosis. To serve that,
mediated site-directed mutagenesis (PSM) was suggested for testing specific
mutations on BRCAi in i9gy by Elizabeth M. Rohlfs et al., a gene causing
hereditary breast cancer. This paper will briefly review BRCAi, assessments
regarding PMS and then mostly focusing on mechanism of BRCAi mutation detection
by using PSM.

Around s to
io% of all breast cancer cases are hereditary and approximately half of them
develop the disease due to hereditary susceptibility gene known as BRCA1 OL BRCAi (BRCA: BReast CAncer
gene). BRCAi is thought to be a tumor suppressor gene that encodes a protein
capable of negatively regulating tumor growth and abnormal function of this
gene may lead to cancer. Since BRCAi are firstly
identified to be
associated with breast cancer risk in ig94. BRCAi began to play an important role in
evaluating newly diagnosed breast cancer patients and others with
high-risk family histories.

With PSM, specific alleles can be identified by changing a sequence to
introduce or remove a restriction site. The sequence is modified by
substituting (or mismatching)  a base
near the mutation  of interest in one of
the two PCR primers. Then, the region containing the mutation site will be
amplified, which will lead to incorporation of the base change in the PCR
product.The PCR products derived from either the wild-type or mutant allele are
able to create or destroy a restriction endonuclease recognition site.
Recognition sites are recognized by a base substitution in one of the primers.
Finally, the alleles are then identified by electrophoresis of the digested PCR

This technique can be
utilized for detection of small insertions, deletions, nonsense and missense mutations. Besides,
i8 5delAG,
538ninsC, Ei •5 oX, and Ri443X mutation are identified by PSM and another
mutation, •• 4del4o, can be detect from the wild-type allele by high-resolution gel electrophoresis
alone. Although this method has not been accepted in clinical testing for
mutations in BRCAi, this strategy may be appropriate because direct testing
for the more common mutations is one component. The PSM technique is evaluated to be sensitive, non-radioactivity requirement, and specific
for individual mutations

conclusion, breast cancer is a popularly fatal disease. Invention of PSM has a
certain meaning for next generation sequencing development for detection of not
only BRCAi mutations. Therefore, people who might develop hereditary breast
cancer have more chance to access early detection of the disease for early
treatment and higher rate of recovery.

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