Re: biopsy results--why DNA testing takes so long

[Guest guest]

Just to give everyone a glimpse into the complexities of DNA testing

and why it takes so long, here is a comment from Wexler, MD,

who has been on the frontline of genetic research mainly because

Huntington's runs in her family.

" To understand the enormous problem of finding a gene somewhere on

an individual's strand of DNA, imagine that a single human genome is

long enough to circle the globe. On this scale, the amount of DNA in

a chromosome would extend for a thousand miles. A gene would span

just one twentieth of a mile, and a disease-causing defect--a point

mutation, a change in only one DNA base pair--could run as short as

one twentieth of an inch. What we are thus searching for is

comparable to a fraction of an inch on the circumference of the

globe! In this immense morass of DNA, finding the exact address of a

gene and pinpointing its fault makes for extremely tough going, and

it requires all of the creativity and ingenuity of everyone engaged

in the quest. "

-- S. Wexler, M.D. in " Clairvoyance and Caution "

http://www.hdfoundation.org/testread/clair.html

> Two years is a long time to wait. Are you waiting for DNA testing?

> What test are they waiting for. I agree with what you said. They

> should tell you the results of the tests as they come in

especially

> if one is going to take a long time.

dawn a

>

>

>

> In , " ohgminion " wrote:

>

> I got partial results after about 8

> > weeks from my muscle biopsy, and am still waiting for results

from

> > additional testing after almost 2 years. > >

> > Take care,

> > RH

[Guest guest]

Just to give everyone a glimpse into the complexities of DNA testing

and why it takes so long, here is a comment from Wexler, MD,

who has been on the frontline of genetic research mainly because

Huntington's runs in her family.

" To understand the enormous problem of finding a gene somewhere on

an individual's strand of DNA, imagine that a single human genome is

long enough to circle the globe. On this scale, the amount of DNA in

a chromosome would extend for a thousand miles. A gene would span

just one twentieth of a mile, and a disease-causing defect--a point

mutation, a change in only one DNA base pair--could run as short as

one twentieth of an inch. What we are thus searching for is

comparable to a fraction of an inch on the circumference of the

globe! In this immense morass of DNA, finding the exact address of a

gene and pinpointing its fault makes for extremely tough going, and

it requires all of the creativity and ingenuity of everyone engaged

in the quest. "

-- S. Wexler, M.D. in " Clairvoyance and Caution "

http://www.hdfoundation.org/testread/clair.html

> Two years is a long time to wait. Are you waiting for DNA testing?

> What test are they waiting for. I agree with what you said. They

> should tell you the results of the tests as they come in

especially

> if one is going to take a long time.

dawn a

>

>

>

> In , " ohgminion " wrote:

>

> I got partial results after about 8

> > weeks from my muscle biopsy, and am still waiting for results

from

> > additional testing after almost 2 years. > >

> > Take care,

> > RH

[Guest guest]

Just to give everyone a glimpse into the complexities of DNA testing

and why it takes so long, here is a comment from Wexler, MD,

who has been on the frontline of genetic research mainly because

Huntington's runs in her family.

" To understand the enormous problem of finding a gene somewhere on

an individual's strand of DNA, imagine that a single human genome is

long enough to circle the globe. On this scale, the amount of DNA in

a chromosome would extend for a thousand miles. A gene would span

just one twentieth of a mile, and a disease-causing defect--a point

mutation, a change in only one DNA base pair--could run as short as

one twentieth of an inch. What we are thus searching for is

comparable to a fraction of an inch on the circumference of the

globe! In this immense morass of DNA, finding the exact address of a

gene and pinpointing its fault makes for extremely tough going, and

it requires all of the creativity and ingenuity of everyone engaged

in the quest. "

-- S. Wexler, M.D. in " Clairvoyance and Caution "

http://www.hdfoundation.org/testread/clair.html

> Two years is a long time to wait. Are you waiting for DNA testing?

> What test are they waiting for. I agree with what you said. They

> should tell you the results of the tests as they come in

especially

> if one is going to take a long time.

dawn a

>

>

>

> In , " ohgminion " wrote:

>

> I got partial results after about 8

> > weeks from my muscle biopsy, and am still waiting for results

from

> > additional testing after almost 2 years. > >

> > Take care,

> > RH

[Guest guest]

http://www.hdfoundation.org/testread/clair/htmlhttp://www.hdfoundation.org/test\

read/clair/html>

Great post and very true. Finding the gene for these diseases is worse than

trying to find a needle in a haystack. I consider anyone who does get the named

gene, very fortunate. Science will perfect this one day and stem cell research

may just be the answer although that is not confirmed. There's a lot of

controversy around stem cell research but my hope is that they can find a way to

have controls that allow the medical profession to proceed with this in an

acceptable manner.

Alice

[Guest guest]

http://www.hdfoundation.org/testread/clair/htmlhttp://www.hdfoundation.org/test\

read/clair/html>

Great post and very true. Finding the gene for these diseases is worse than

trying to find a needle in a haystack. I consider anyone who does get the named

gene, very fortunate. Science will perfect this one day and stem cell research

may just be the answer although that is not confirmed. There's a lot of

controversy around stem cell research but my hope is that they can find a way to

have controls that allow the medical profession to proceed with this in an

acceptable manner.

Alice

[Guest guest]

http://www.hdfoundation.org/testread/clair/htmlhttp://www.hdfoundation.org/test\

read/clair/html>

Great post and very true. Finding the gene for these diseases is worse than

trying to find a needle in a haystack. I consider anyone who does get the named

gene, very fortunate. Science will perfect this one day and stem cell research

may just be the answer although that is not confirmed. There's a lot of

controversy around stem cell research but my hope is that they can find a way to

have controls that allow the medical profession to proceed with this in an

acceptable manner.

Alice

[Guest guest]

Maybe I should add that Dr. Wexler wrote this paper in 1992, though

her analogy still holds true for today. Since then, the human genome

map has been more or less completed and many genes mapped. Now the

hunt is getting down to the level of the point mutations for

individual diseases: the single change in the base pairs, the 1/20

of an inch, the needle in the haystack.

As an example, in just one mito disorder--CPT II deficiency--about

30 different disease-causing mutations have been found in the CPT2

gene at this point. We are making progress! There is hope!

Barbara

> >

> > I got partial results after about 8

> > > weeks from my muscle biopsy, and am still waiting for results

> from

> > > additional testing after almost 2 years. > >

> > > Take care,

> > > RH