Since the discovery of genes like RB, p53, NF1, ret, HNPCC
mismatch repair genes, BRCA1, and BRCA2, it has become possible to
analyse DNA to predict risk of cancer. However, there are many
obstacles to overcome before any meaningful testing can be applied
to the general population. The mutational heterogeneity for these
genes pose a considerable technical challenge. It is often
necessary to sample every nucleotide of the coding region and the
promoter to identify the mutations. False positive results can
present a thorny problem. Sequential alterations may turn out to
be benign variants or allelic variations rather than disease
causing mutations. Unless proven interventions are available and
the test is sensitive, specific and inexpensive, it is not
realistic to introduce such tests to the general population.
Therefore, genetic testing is not considered except for high
risk individuals according to their family history. If
proven intervention do not exist as in the Li-Fraumeni syndrome,
then the value of genetic testing is limited.
However, genetic testing brings more benefits than risks for
some cancer syndromes. These include multiple endocrine neoplasia
type 2 and von Hippel-Lindau disease. Tests for BRCA 1, BRCA 2,
and HNPCC genes fall in the gray zone.
As more susceptibility genes are identified, better answers
become available about the effectiveness of interventions. One day
genetic testing will move into the mainstream medicine. Every
physician of the future will need to have the skill as a genetic
counsellor.
If you have questions related to this article you may e-mail me
at doctor@soontongkiong.com quoting the contents of the article.
About the author
DR SOON is a medical practitioner. He holds four degrees. MBBS
(University of Malaya), MBA (University of East Asia), LLB (Hons)
(University of Wolverhampton), Master of Medicine (Edith Cowan
University
:
Dr SOON is the owner of AskMyVisitor.com and MyScriptDoctor.com
where you can find the most up-to-date advice and information
on
many medical, health and lifestyle topics.
