Re: time of DNA results

[Guest guest]

In a message dated 12/12/00 06:33:24 PM Pacific Standard Time,

liliwigg@... writes:

<< Can someone please tell me why it takes so long to get the DNA CMT test

results back? >>

Well Gretchen they have to grow a sheep in your likeness. If the sheep walks

funny or Diffrent " You have CMT.

[Guest guest]

Gretchen:

Lamar here,

Most lab work is done by machine, and only take minutes to perform...... DNA

testing is an entirely different process. The cells must be separated and

subjected to an electrical treatment. Then specimens are prepared. Then they

are viewed with electron microphotography, and photographs made, then the

chromosomes are separated and identified, then the chromosomes are subjected to

an electrical analysis and films made (like the ones many saw in OJ's trial).

The next step is that they must be computer evaluated as well as by human eyes.

Each step can take several days. It is like painting something, the first coat

must dry before the second is applied. To top it off Athena does DNA testing

for literally hundreds of things. having worked with early chromosome

evaluations as well as some with DNA photography, it is surprising that they get

the tests done as fast as they do.

Other labs are doing some CMT testing, but they are in early stages of

development and the accuracy has not been proven. Athena developed the tests

and is the only lab which CMT researchers will accept results from. That should

speak for itself.

----- Original Message -----

From: Gretchen Glick

egroups

Sent: Tuesday, December 12, 2000 09:24 PM

Subject: [] time of DNA results

Can someone please tell me why it takes so long to get the DNA CMT test

results back? I mean this IS a blood test, right? I know it has to be

shipped, and all but why do people have to wait so long for the results?

When my new neuro asked if I had the test I said no, already had 3 CMT

diagnosis, he said, let me know now, there's a lab in Santa

(Calif.) doing it that is fast. I am assuming he meant fast like in a

few days. Do people have to wait so long because the Dr. has to give the

patient the results and it takes time to get an appointment? It just

seems to be tested for something like CMT and then be told you have to

wait 8 weeks for the results could be very unsettling for the patient.

~ G

eGroups Sponsor

[Guest guest]

In a message dated 12/12/2000 11:01:55 PM Central Standard Time,

warrenre@... writes:

> > Can someone please tell me why it takes so long to get the DNA CMT

> test

> > results back?

>

> Gretchen,

>

How long is it taking? I had one at the end of October and got the results at

the MDA clinic today. Dr. had told me that it could be 4 to 6 weeks to

get a report back, so they made an appt. for 8 weeks after the test. By the

way, I have type C, which apparently means they haven't mapped it yet. C

[Guest guest]

> Can someone please tell me why it takes so long to get the DNA CMT

test

> results back?

Gretchen,

All I can offer is a couple educated guesss (ok, maybe not so

educated) but here goes. I have two theories.

1. DNA testing does require some time. How much time, I do not know

but from hearing about DNA testing in regards to court trials (I

listen to court tv quite a bit) the process is more complicated and

time consuming than many other everyday blood tests.

2. MDA calendars: The MDA clinic at Duke is open one day a week. I

am guessing in less populated areas the clinics may be open only once

a month. I'm not sure about this but it seems reasonable. In any

case, even a one-day-a-week clinic in a metroplitan area would have a

backlog of appointments.

Ruth

[Guest guest]

,

Lamar here,

You need to check further. There is no just " type C " . The Types are numbered

Type, 1, 2, 3 etc. Each one has subtypes that are lettered A, B, C etc.

----- Original Message -----

From: C1520@...

egroups

Sent: Wednesday, December 13, 2000 04:04 AM

Subject: Re: [] Re: time of DNA results

In a message dated 12/12/2000 11:01:55 PM Central Standard Time,

warrenre@... writes:

> > Can someone please tell me why it takes so long to get the DNA CMT

> test

> > results back?

>

> Gretchen,

>

How long is it taking? I had one at the end of October and got the results at

the MDA clinic today. Dr. had told me that it could be 4 to 6 weeks to

get a report back, so they made an appt. for 8 weeks after the test. By the

way, I have type C, which apparently means they haven't mapped it yet. C

[Guest guest]

That's all the doctor told me. c

[Guest guest]

Hi,

I see you have some questions about the time it takes to perform CMT

DNA testing. I would like to respond in the general case about turn-

around times for such tests sent to Athena Diagnostics, and genetic

labs in general. Please note that I will not answer questions about

any specific patient result.

There are currently five genetic tests for CMT that employ some labor

and equipment intesive technologies to determine if there is anything

wrong in the four known CMT-related genes (PMP-22, MPZ (A.K.A. P0),

Connexin32, and EGR2). Abnormalities in these genes can cause a

variety of motor-sensory neuropathy presentations ranging from mild

(nearly asymptomatic) hereditary liability for pressure palsy, to the

most severe congenital hypomyelination neuropathy.

For the classic presentation of CMT, it is very difficult (basically

impossible) to establish a CMT subtype without a molecular test. A

physician can extablish whether your CMT1 or CMT2 by

electrophysiology, but to further classify by genetics requires the

tests.

In the current CMT nomenclature, there are 4 subtypes of CMT1, 2

subtypes of CMTX (which may look like CMT1 or CMT2), 5 subtypes of

CMT2, 2 subtypes of Dejerine Sottas, plus CHN, HNPP, and the

recessive forms (Curr Opin Neurol. 1999 Oct;12(5):603-16).

The genes do not map specifically to the subtypes as was once

thought. For example, CMT1B is caused by mutations in MPZ, and

initially that was thought to be the only clinical presentation for

mutations in MPZ. We now know that mutations in MPZ can cause CMT1B,

CMT2E, Dejerine Sottas type B, and Congenital Hypomyelination

Neuropathy. Other CMT genes have similar variations.

Consequently, it is more informative (and quicker) to request these

tests simultaneously in individuals where no family member has ever

been tested (where the specific mutation in the family has not yet

been identified).

Since there are multiple tests involved, with varying turn-around

times, the longest common denominator will hold back the profile.

(True for any lab, any test or profile).

The technologies used are far more complicated than a urine dip-stick

or hematocrit. Four of the five tests involve sequencing the genes.

Sequencing is basically a genetic " spell-check " of a specific gene.

Athena's Complete CMT Evaluation sequences four CMT genes, plus

performs another test. This other test is called the PMP22

(duplication/deletion) DNA Test, which counts the number of PMP22

genes in the patient's specimen. If you have two copies, your CMT is

not due to an abnormal number of PMP22 genes. One copy means you

have HNPP, three copies means you have CMT1A.

All of these tests are time consuming and expensive to run. What you

get from this is a complete picture of your CMT genotype with extreme

certainty and accuracy. Furthermore, once a family member has been

molecularly diagnosed, it is no longer necessary to have the full

battery run on other family members, thus reducing the cost (and

turnaround time) considerably.

I will be happy to answer any other general questions about CMT DNA

testing, and encourage anyone considering genetic testing to consult

a genetic counselor to make sure thatyou know what your getting

into. Your doctors are very smart and educated, but many of the

genetic advances have occured after they left medical school. Do

them a favor and ask for the referral to a genetic counselor.

Bertolino

Neurogenetic Product Manager

Athena Diagnostics, Inc.

> Can someone please tell me why it takes so long to get the DNA CMT

test

> results back? I mean this IS a blood test, right? I know it has to

be

> shipped, and all but why do people have to wait so long for the

results?

> When my new neuro asked if I had the test I said no, already had 3

CMT

> diagnosis, he said, let me know now, there's a lab in Santa

> (Calif.) doing it that is fast. I am assuming he meant fast like in

a

> few days. Do people have to wait so long because the Dr. has to

give the

> patient the results and it takes time to get an appointment? It just

> seems to be tested for something like CMT and then be told you have

to

> wait 8 weeks for the results could be very unsettling for the

patient.

> ~ G

[Guest guest]

Thanks Lamar, that was a quick and easy to understand explaintion of DNA

testinv, and we are all thankful for Athena Labs. jr

PS Mery Christmas to all of you!

[Guest guest]

> Can someone please tell me why it takes so long to get the DNA CMT test

> results back?

I work in the office of a geneticist. Patients are told it takes 4-6

weeks for all or most genetic test results from the lab here at a

University. My understanding is that genetic tests are labor- and

time-intensive. I would think there is some backlog due to that

intensive work, adding to the time. The response from Athena

Diagnostics was excellent. Genetic counseling before being tested is a

good idea -- there may be a number of issues and subtleties we

wouldn't think of without the professional genetics counselor's input.