Precision medicine has the potential to change fundamentally how health care is practiced, but requires a health care workforce that understands the complexities of this field. One important component of Precision Medicine is the use of an individual’s genomic information to offer targeted treatment, tailored to the individual. Our course aims to provide participants with some baseline knowledge of genomics, an overview of the clinical applications of genomic medicine, the skills to evaluate the clinical validity and utility of new tests, and an appreciation of the associated ethical and social issues inherent in this field. The course is geared toward practicing health care providers, although it should be accessible to anyone with a background in the biological sciences and a basic understanding of genetics. It is designed to be succinct and clinically-focused, offering both conceptual and practical information about real-world applications of genomics. Two lessons offer a basic primer on molecular genomics relevant to the individual patient as well as to patient populations. The remaining five lessons focus on five applications of genomics and present the material as case studies, highlighting the strengths, limitations, and issues that arise in the use of each test.
Week 5 - Module 4: Case Scenario - Alzheimer's Example
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From the course by University of California, San Francisco
Genomic and Precision Medicine
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From the lesson
Week 5
This week Dr. Mendelsohn joins me to roll play some scenarios to teach you about predictive tests for common, complex diseases and direct-to-consumer testing.
Meet the Instructors
Jeanette McCarthy, MPH, PhDAdjunct Associate Professor
UCSF Department of Medicine
Robert L. Nussbaum, MDChief and Professor of Medicine
Division of Genomic Medicine
[BLANK_AUDIO].
In this third case scenario, the physician has an older patient
who is worried that he may, may be developing Alzheimer's disease.
Since he has a family history of dementia.
The physician heard about a genetic test for
APOE that may help predict risk of Alzheimer's disease.
And was wondering whether it's a good idea or not to have the patient tested.
Before the physician talks to the patient, he consults with a medical geneticist.
Hey, Bryce.
What can I do for you?
>> Thank you once again for your, your assistance.
So I told you a little bit about this gentleman who
wants to get a better idea if he might develop Alzheimer's.
And he suggested the APOE test and asked me if I would order it.
I don't know a lot about it.
Is this a good test?
Is this test have a good predictive value for for Alzheimer's disease.
>> Well, in terms of common complex diseases and genetic risk factors.
That APOE association with Alzheimer's disease, is
one of the most strongest associations, we've seen.
There is this e4 allele, which increases your risk of Alzheimer's disease.
If you have one copy, you have about a fourfold increased risk.
If you have two copies, you have anywhere from like
a 10 to 20 fold increased risk of Alzheimer's disease.
So, it is a quite a good genetic marker in that sense, but it is good to keep
in mind that it is neither necessary or sufficient for Alzheimer's.
So there are a lot of people out there walking around
with an APO e4 allele who will never get Alzheimer's disease.
>> And I guess there are probably people
who do have Alzheimer's, but don't have that particularly.
>> That's right, there are other causes.
Genetics is no.
>> It's a major predictor, but it's not the whole story.
>> That's right.
>> Okay, okay.
Would it, would it be different if the patient had symptoms of early dementia.
Would it, would it be more likely that he would go on
to have Alzheimer's if this gene test came back with, at risk alleles.
>> well, you may be referring to some of the guidelines that have come out.
>> Mm-hm.
>> Which suggest that, if you're going to test for APOE and Alzheimer's Disease.
That, you should do it in the context of a patient who has dementia already.
>> Okay.
>> That's primarily because, there is
some risk associated with depression and anxiety.
If a person comes back with a positive test
result in the absence of signs and symptoms of dementia.
So the guidelines that say you should do it in the context of dementia are
really trying to alleviate some of the psychological
distress of testing in say a general population.
>> Okay, I'm glad you brought up the psychological issues.
I was thinking for a second if there's such
a strong association, why, why not get everybody tested?
>> Right.
>> And I mean it sounds like maybe there'd be some downside to that?
>> Oh definitely because like I said there are a lot of people
walking around who have this APOE-4
allele, who will never get Alzheimer's Disease.
And you don't want to completely stress them out.
>> Got it, got it, okay.
So I think that this guy is going to want to know,
he's going to, this is what he has been bothering me about.
How do I, how do I actually order this test?
>> Well, before you order this test you need to think about a few things.
>> Okay.
>> First of all, you need to think about
whether this information, if it gets out, for example.
Might it affect his long term, disability
insurance or life insurance, the things like that.
>> What about the GINA law that was passed a few years ago?
>> Right, so GINA, the Genetic Information Non-Discrimination Act.
>> Mm-hm, yes.
>> Was passed in 2008.
>> Mm-hm.
That only covers health insurance.
>> Oh.
>> Right?
>> Okay?
>> So you, you can't discriminate against someone.
In other words, you can't deny them coverage or change their premiums.
>> Mm-hm.
>> Based on a genetic condition.
>> But life insurance, disability insurance.
>> That's different.
>> Not the same.
That's different.
>> Okay >.
GINA also has some previsions for work place discrimination things like that.
But not, not for the long term disability.
>> Got it, okay.
And then but if he's okay with that.
He's already go this insurance tucked away and I still want to order this test.
How do I fInd the, the right place to send it?
You know, a place that will be covered by
his insurance, that will, that I, is local etc.
>> Well the best place to start would
be this website that houses the genetic testing registry.
>> Mm-hm.
>> So this is a a website that the
National Institute of Health and the U.S. put together.
It's a voluntary submission of laboratory tests by the testing facilities.
But it's an excellent resource for learning about what
tests are out there and where to order them.
Should we take a look at it?
>> Yes please, absolutely.
>> Okay.
So, I've searched the database.
And you can search on, on whether, you can search on the gene name.
You can search on the disease.
>> Okay
>> And, and when I put that information into the website, it pulls
up a number of different tests and a number of different testing labs.
>> Yes, yes that's a bunch.
>> Right.
And, and you can filter.
>> Mm-hm.
>> To, on a number of different factors.
One thing that's not shown on our screen here, is
that you can filter, based on where the testing lab is.
Right?
So, so the location might be important for you.
You might want to test in the, in a laboratory in the U.S., for example.
>> Mm-hm.
>> But like I said, there are a number of different tests, that come up here.
Some of them are for multiple genes.
So, do you think you'd be interested in looking
at bunch of different genes or just a APOE gene.
>> I, I'm, I mean I just learned about this,
so I'm going to stick with the APOE for now.
>> Okay.
>> But I'm interested to know what the genes are doing
in these, these gene panels and how they help or don't help.
>> Right.
So, we, we can certainly explore what these
other genes do and if you might be interested.
But, but for this scenario where you >> Mm-hm.
>> He expressed an interest in this one particular gene
>> Mm-hm.
>> Let's just focus on that one.
>> Sounds good.
>> So the APOE gene alone, you have another couple of choices to make.
You have APOE gene alone where you do targeted variance analysis.
And then you have another test here, for the
APOE gene, where you could sequence the whole gene.
>> Okay.
So it's not just the gene, there's more detail, beyond that.
I have to know the gene and what I want to test for in the gene.
>> Well, in some cases, yes.
In this specific example, you probably want to focus on targeted
variant detection because, there are specific locations in the genes.
Specific polymorphisms.
>> Mm-hm.
>> This APOE-4 allele for which we know that a
person who has that has an increased risk of Alzheimer's Disease.
If you do sequence analysis of the whole gene.
You have the ability to detect any new variant in that
gene, but you're not necessarily know what to make of that information.
>> Okay, okay.
>> Right?
So you find a new genetic variant, so what, how are you
going to know if it increases his risk of Alzheimer's disease or not?
>> Okay.
>> So, in this case.
>> So this one just tests for the one snip that tells me that it's APOE-4.
>> That's right.
Well, technically speaking APOE-4 is defined by the combination of two snips.
>> Two snips, okay.
>> But that's irrelevant.
>> Okay.
>> But, the point is that.
>> That the report will only look at that.
>> It will only look at that.
>> Okay.
And it will give me extra information that I won't know.
>> That's right.
>> How to interpret.
Okay.
>> No extra information.
>> Okay.
>> Okay?
>> Okay.
>> Anything else you want to know?
>> well, I had a few questions, about, what happens after we get those test done?
You said that it's not guaranteed that he'll get Alzheimer's disease
if he has these alleles, but his risk will be higher.
In my practice, I actually, you know, he's an
older gentleman I take care of his middle aged son.
It's going to be kind of weird knowing that, that he has these risk alleles.
And his son could've inherited them.
I guess I'm not supposed to this, I just had a sort of odd situation.
Is there any guidance you can give me in that, in that context?
>> Yeah, well, so there are a couple of things that I want to tell you.
One, with respect to the son, you've
got to be really careful with genetic information.
Because, for this gene in particular, a lot
of people don't want to know their results.
And you really have to respect a persons right to not know a genetic result.
So, if you go through with these testing for this gentleman.
He needs to be very conscious of the fact that if
he tests positive, that information, he might not want to share that.
Or he might want to check with his offspring to
see if they would also want to be tested or not.
So, that's one thing.
And the other is you know, you mentioned earlier about
how there was nothing you can really do about Alzheimer's disease.
>> Mm-hm.
>> If you were tested, if you test positive
>> Yeah.
>> So what?
What, what information am I going to get from this?
And the point is that, you have to consider the personal utility
>> Mm-hm.
>> Of tests like this as well.
You have a patient who, who knows that, if he tests positive.
He may get Alzheimer's disease and that there's nothing he can do about it.
But for him he may get some great relief knowing that you
know, there's a genetic basis and, and that he might be at risk.
He may be able to do some planning for, for the future.
Get his affairs in order something that if he chooses to do that.
So you know, that's the other side here is
that even though there might be any clinical utility.
That personal utility is increasingly being
recognized as something of value to patients.
>> Sounds like there needs to be a pretty significant
conversation before I send this test, and probably afterwards as well.
>> Absolutely.
Absolutely, you should you should talk to him about
this, make sure he knows all of the risks.
The psychological risks, the economic risks, things
like that, as well as the potential benefits.
>> Okay, okay.
Well thank you so much.
>> Great.
>> I'll let you know what comes of this.
And how, how how this goes forward with him.
>> Good luck.
>> Thank you.
>> Well we hope we conveyed the following ideas to you in this third case scenario.
Frist of all what is GINA, the genetic information nondiscrimination act.
What it does and doesn't cover.
>> The fact that personal utility is
being increasingly recognized as rational for genetic testing.
Where to find information about available for genomic tests.
And finally, the utility of targeted variant
analyses verses sequencing entire coding regions of genes.
[BLANK_AUDIO]
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