Now, a quick lecture on genetic counseling and prenatal diagnosis. The field of genetic counseling
or clinical genetics has changed a lot in recent years due to the advent of all these new technologies
and the discovery of more and more genes. But it is going to involve things like counseling
and taking family histories which is more traditional, as well as calculating risk assessments
and pedigree analysis, molecular diagnostics and the whole genome diagnostics. These techniques
all come together. Generally now, we have genetic counselors that take care of the genetic counseling
part of the practice. But either way, in considering genetic counseling, whichever degree of it
that you might get into, you would be considering not only the original patient but we need
to be concerned with the future children of that patient as well as other family members of that patient.
These are all the people that come into the picture when genetic counseling for one individual.
Not only do we need to consider the diagnosis part but we also need to consider the psychological
aspects as well as social aspects and medical aspects of treating or managing genetic disorders.
So, this is now the whole field of clinical genetics. As I said, the majority of times, this is taken care of
by genetic counselors. Genetic counseling is a burgeoning field now in the United States, the UK,
and Canada. Very common if someone goes in and has a family history, say of breast cancer
or a colon cancer for the doctor to refer them to genetic counseling. A lot of this can be done
by sending in samples. You can send them in from your regular doctor. As a doctor, you would perhaps
be in charge of taking samples and sending them and then referring the client out to genetic counseling
much as you would work with other members of a team, surgeons, and internists, and so on
and so forth in order to provide a full spectrum of genetic care. Today, both the United States
and Canada have specific boards of genetic counselors. People become board-certified
genetic counselors. Often they’re nurses or physician’s assistants that specialize in genetics
but they don’t necessarily have to be in those particular roles. They could be purely in the role
of genetic counseling because clearly, genetic counseling not only entails counseling
and the genetic diagnosis but lots of other fields as well. So, it’s becoming a very, very specialized filed.
As a doctor yourself, you probably won’t be involved in too much of the detail of genetic counseling
but referring patients is most important. Who should be referred for genetic counseling?
You probably are pretty familiar with anyone having a family history. If you’ve got to an adult life,
anyone having a family history of genetic disorder would be a great candidate for genetic testing.
Of course, in considering referring for genetic testing, you want to consider their own background
and values and whether it’s something that’s suitable for them. Ultimately, it is the patient themselves
that would make that decision. Now, it’s highly recommended that women interested in becoming
pregnant or having a pregnancy over 35 years of age have genetic counseling because there are so many
tests available to us now. We can do preimplantation genetic diagnosis, all sorts of techniques to prevent
implantation of an embryo that may have genetic predisposition or actual genetic mutation itself.
Of course, we might want to refer a mother who’s had repeated miscarriages or has had a previous child
with a genetic disorder so that we can also do some work on the frontend to prevent implantation
of an embryo that has defects. As we’ve explored before in the molecular genetics course,
there are so many techniques available for genetic diagnosis including gene panels where we can
examine hundreds of genes at a time, sort of probe for genes. Targeted sequencing where we can say,
hey, does this person have this particular gene and target probes to that to label them as we see in FISH.
Whole exome sequencing, so we take all the exons and sequence those to see what genes might be there.
Then, whole genome sequencing; now, with the dropping cost of whole genome sequencing,
that is going to become more of a viable option for genetic counselors and doctors alike.
All of these advents in DNA technologies have really lent themselves to a bright future for genetic testing.
Thinking about whole genome sequencing, this is a graph from National Institute of Health
and the Human Genome Research Institute. I thought I’d do a quick search and see how the prices
have changed over the years. For example, back in 2006, it cost 20 to 25 million dollars to sequence
one human genome. By the end of 2015, the price had dropped to below $1,500.
In the beginning of 2016, I think it hit its first sub $1,000 cost per person to sequence a genome.
It’s becoming more and more available and more and more of a cost effective technique
to sequence a whole genome. I think with the advent of whole genome sequencing,
we need to keep our eyes open for the possibilities that it can offer us.