Zygosity

Janet,
My twins are both girls . . . Morgan is a girl. I don't know if you were
referring to them as bg twins.

When they do a DNA test they test 6-8 different DNA strands where
differences are common to most individuals. The informational sheet I got
from the lab says:
"Usually there are millions of differences in the DNA 'spelling' of one
person's genes compared to another person's genes. The only exception is in
the case of monozygotic (identical) twins who have the same spelling for all
3 billion letters (with rare exceptions). Even siblings or close relatives
have hundreds of thousands of differences in their DNA code."

It goes on to say if the areas they test match up for at least six or more
sites then the twins are monozygotic with a greater then 99% probability.
Therefore, I think this % is referring to the test accuracy (?). It also
says if they are different for two or markers then the twins are dizygotic
(fraternal).

They tested my girls on 8 DNA markers and all eight were a match so the
probability that they are identical has a greater then 99% probability the
report states.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"multimom4" wrote in message
news:lg7ub.173192$9E1.893856@attbi_s52...
Um ... at risk of showing my ignorance here ("btw, are your bg twins
identical?") ... is 99.9 "identical"? And if so, is 98.6 identical, too?
And if so, where the heck is the cut-off?

--Janet
Elliot, Hanna, Connor (10/21/96)
and Holly (4/4/01)

"Kender" wrote in message
news:iaYsb.197369$Fm2.182546@attbi_s04...
My girls each had their own placentas. They also had their own sacks.
Morgan's water broke but Megan's had to be broken. We had their DNA
tested
when they were 2.5 years old. They are 99.9% alike in DNA.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"KimandJuan" wrote in message
...
I am curious.....

Are there any same sex twins that were "bi-chorial" with two
separate
placentas and "BI-amniotic" with two separate amniotic sacs, and later
DNA
tested later and proved to be identical in this news group. I wonder
how
common it is. What has peaked my interest is the Harvard study that I
mentioned earlier has offered to do a DNA test as compensation for
participating. So, it has me thinking about the girls zygosity again.


~Kimberly
Mommy to Alexis Iliana 07/17/99 and
Emma Elidia & Aislyn Gabriela 10/01/02
come see us...
http://www.babiesonline.com/babies/a/aislynemma/

I know they're girls, Erin, ... else they wouldn't have fought *quite* so
hard over the Easter dresses, would they??? :-) I was just making fun of
myself not knowing how identical "identical" actually is (*like* those
people in the mall who ask if bg twins are identical).

From your answer, I guess then they are saying that since they test the
most-often-different 6-8 strands, then if *those* are identical, chances are
huge (99.9%, in your case) that the rest of the DNA is gonna be identical,
too. Very cool. Thanks for the info.

--Janet
Elliot, Hanna, Connor (10/21/96) -- and who barely share *any* DNA, it
sometimes seems to me :-)
and Holly (4/4/01)


"Kender" wrote in message
news:G39ub.225303$Tr4.669139@attbi_s03...
Janet,
My twins are both girls . . . Morgan is a girl. I don't know if you were
referring to them as bg twins.

When they do a DNA test they test 6-8 different DNA strands where
differences are common to most individuals. The informational sheet I got
from the lab says:
"Usually there are millions of differences in the DNA 'spelling' of one
person's genes compared to another person's genes. The only exception is
in
the case of monozygotic (identical) twins who have the same spelling for
all
3 billion letters (with rare exceptions). Even siblings or close relatives
have hundreds of thousands of differences in their DNA code."

It goes on to say if the areas they test match up for at least six or more
sites then the twins are monozygotic with a greater then 99% probability.
Therefore, I think this % is referring to the test accuracy (?). It also
says if they are different for two or markers then the twins are dizygotic
(fraternal).

They tested my girls on 8 DNA markers and all eight were a match so the
probability that they are identical has a greater then 99% probability the
report states.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"multimom4" wrote in message
news:lg7ub.173192$9E1.893856@attbi_s52...
Um ... at risk of showing my ignorance here ("btw, are your bg twins
identical?") ... is 99.9 "identical"? And if so, is 98.6 identical,
too?
And if so, where the heck is the cut-off?

--Janet
Elliot, Hanna, Connor (10/21/96)
and Holly (4/4/01)

"Kender" wrote in message
news:iaYsb.197369$Fm2.182546@attbi_s04...
My girls each had their own placentas. They also had their own sacks.
Morgan's water broke but Megan's had to be broken. We had their DNA
tested
when they were 2.5 years old. They are 99.9% alike in DNA.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"KimandJuan" wrote in message
...
I am curious.....

Are there any same sex twins that were "bi-chorial" with two
separate
placentas and "BI-amniotic" with two separate amniotic sacs, and
later
DNA
tested later and proved to be identical in this news group. I
wonder
how
common it is. What has peaked my interest is the Harvard study that
I
mentioned earlier has offered to do a DNA test as compensation for
participating. So, it has me thinking about the girls zygosity
again.


~Kimberly
Mommy to Alexis Iliana 07/17/99 and
Emma Elidia & Aislyn Gabriela 10/01/02
come see us...
http://www.babiesonline.com/babies/a/aislynemma/

I know they're girls, Erin, ... else they wouldn't have fought *quite* so
hard over the Easter dresses, would they??? :-) I was just making fun of
myself not knowing how identical "identical" actually is (*like* those
people in the mall who ask if bg twins are identical).

From your answer, I guess then they are saying that since they test the
most-often-different 6-8 strands, then if *those* are identical, chances are
huge (99.9%, in your case) that the rest of the DNA is gonna be identical,
too. Very cool. Thanks for the info.

--Janet
Elliot, Hanna, Connor (10/21/96) -- and who barely share *any* DNA, it
sometimes seems to me :-)
and Holly (4/4/01)


"Kender" wrote in message
news:G39ub.225303$Tr4.669139@attbi_s03...
Janet,
My twins are both girls . . . Morgan is a girl. I don't know if you were
referring to them as bg twins.

When they do a DNA test they test 6-8 different DNA strands where
differences are common to most individuals. The informational sheet I got
from the lab says:
"Usually there are millions of differences in the DNA 'spelling' of one
person's genes compared to another person's genes. The only exception is
in
the case of monozygotic (identical) twins who have the same spelling for
all
3 billion letters (with rare exceptions). Even siblings or close relatives
have hundreds of thousands of differences in their DNA code."

It goes on to say if the areas they test match up for at least six or more
sites then the twins are monozygotic with a greater then 99% probability.
Therefore, I think this % is referring to the test accuracy (?). It also
says if they are different for two or markers then the twins are dizygotic
(fraternal).

They tested my girls on 8 DNA markers and all eight were a match so the
probability that they are identical has a greater then 99% probability the
report states.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"multimom4" wrote in message
news:lg7ub.173192$9E1.893856@attbi_s52...
Um ... at risk of showing my ignorance here ("btw, are your bg twins
identical?") ... is 99.9 "identical"? And if so, is 98.6 identical,
too?
And if so, where the heck is the cut-off?

--Janet
Elliot, Hanna, Connor (10/21/96)
and Holly (4/4/01)

"Kender" wrote in message
news:iaYsb.197369$Fm2.182546@attbi_s04...
My girls each had their own placentas. They also had their own sacks.
Morgan's water broke but Megan's had to be broken. We had their DNA
tested
when they were 2.5 years old. They are 99.9% alike in DNA.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"KimandJuan" wrote in message
...
I am curious.....

Are there any same sex twins that were "bi-chorial" with two
separate
placentas and "BI-amniotic" with two separate amniotic sacs, and
later
DNA
tested later and proved to be identical in this news group. I
wonder
how
common it is. What has peaked my interest is the Harvard study that
I
mentioned earlier has offered to do a DNA test as compensation for
participating. So, it has me thinking about the girls zygosity
again.


~Kimberly
Mommy to Alexis Iliana 07/17/99 and
Emma Elidia & Aislyn Gabriela 10/01/02
come see us...
http://www.babiesonline.com/babies/a/aislynemma/

Janet,
Sorry, my mind is foggy from all the sickness around here. I can't think
straight and didn't get the sarcasm at all.

Until I reread the letter from the lab for my post I hadn't thought of it as
probabilities for the test results, just DNA vs. DNA probabilities too. Now
we both know.
--
Erin
Morgan and Megan 2/15/97 "Those damn Easter dresses"
Evan 5/14/00



"multimom4" wrote in message
news:5Wfub.171541$mZ5.1214175@attbi_s54...
I know they're girls, Erin, ... else they wouldn't have fought *quite* so
hard over the Easter dresses, would they??? :-) I was just making fun of
myself not knowing how identical "identical" actually is (*like* those
people in the mall who ask if bg twins are identical).

From your answer, I guess then they are saying that since they test the
most-often-different 6-8 strands, then if *those* are identical, chances
are
huge (99.9%, in your case) that the rest of the DNA is gonna be identical,
too. Very cool. Thanks for the info.

--Janet
Elliot, Hanna, Connor (10/21/96) -- and who barely share *any* DNA, it
sometimes seems to me :-)
and Holly (4/4/01)


"Kender" wrote in message
news:G39ub.225303$Tr4.669139@attbi_s03...
Janet,
My twins are both girls . . . Morgan is a girl. I don't know if you were
referring to them as bg twins.

When they do a DNA test they test 6-8 different DNA strands where
differences are common to most individuals. The informational sheet I
got
from the lab says:
"Usually there are millions of differences in the DNA 'spelling' of one
person's genes compared to another person's genes. The only exception is
in
the case of monozygotic (identical) twins who have the same spelling for
all
3 billion letters (with rare exceptions). Even siblings or close
relatives
have hundreds of thousands of differences in their DNA code."

It goes on to say if the areas they test match up for at least six or
more
sites then the twins are monozygotic with a greater then 99%
probability.
Therefore, I think this % is referring to the test accuracy (?). It also
says if they are different for two or markers then the twins are
dizygotic
(fraternal).

They tested my girls on 8 DNA markers and all eight were a match so the
probability that they are identical has a greater then 99% probability
the
report states.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"multimom4" wrote in message
news:lg7ub.173192$9E1.893856@attbi_s52...
Um ... at risk of showing my ignorance here ("btw, are your bg twins
identical?") ... is 99.9 "identical"? And if so, is 98.6 identical,
too?
And if so, where the heck is the cut-off?

--Janet
Elliot, Hanna, Connor (10/21/96)
and Holly (4/4/01)

"Kender" wrote in message
news:iaYsb.197369$Fm2.182546@attbi_s04...
My girls each had their own placentas. They also had their own
sacks.
Morgan's water broke but Megan's had to be broken. We had their DNA
tested
when they were 2.5 years old. They are 99.9% alike in DNA.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"KimandJuan" wrote in message
...
I am curious.....

Are there any same sex twins that were "bi-chorial" with two
separate
placentas and "BI-amniotic" with two separate amniotic sacs, and
later
DNA
tested later and proved to be identical in this news group. I
wonder
how
common it is. What has peaked my interest is the Harvard study
that
I
mentioned earlier has offered to do a DNA test as compensation for
participating. So, it has me thinking about the girls zygosity
again.


~Kimberly
Mommy to Alexis Iliana 07/17/99 and
Emma Elidia & Aislyn Gabriela 10/01/02
come see us...
http://www.babiesonline.com/babies/a/aislynemma/

Janet,
Sorry, my mind is foggy from all the sickness around here. I can't think
straight and didn't get the sarcasm at all.

Until I reread the letter from the lab for my post I hadn't thought of it as
probabilities for the test results, just DNA vs. DNA probabilities too. Now
we both know.
--
Erin
Morgan and Megan 2/15/97 "Those damn Easter dresses"
Evan 5/14/00



"multimom4" wrote in message
news:5Wfub.171541$mZ5.1214175@attbi_s54...
I know they're girls, Erin, ... else they wouldn't have fought *quite* so
hard over the Easter dresses, would they??? :-) I was just making fun of
myself not knowing how identical "identical" actually is (*like* those
people in the mall who ask if bg twins are identical).

From your answer, I guess then they are saying that since they test the
most-often-different 6-8 strands, then if *those* are identical, chances
are
huge (99.9%, in your case) that the rest of the DNA is gonna be identical,
too. Very cool. Thanks for the info.

--Janet
Elliot, Hanna, Connor (10/21/96) -- and who barely share *any* DNA, it
sometimes seems to me :-)
and Holly (4/4/01)


"Kender" wrote in message
news:G39ub.225303$Tr4.669139@attbi_s03...
Janet,
My twins are both girls . . . Morgan is a girl. I don't know if you were
referring to them as bg twins.

When they do a DNA test they test 6-8 different DNA strands where
differences are common to most individuals. The informational sheet I
got
from the lab says:
"Usually there are millions of differences in the DNA 'spelling' of one
person's genes compared to another person's genes. The only exception is
in
the case of monozygotic (identical) twins who have the same spelling for
all
3 billion letters (with rare exceptions). Even siblings or close
relatives
have hundreds of thousands of differences in their DNA code."

It goes on to say if the areas they test match up for at least six or
more
sites then the twins are monozygotic with a greater then 99%
probability.
Therefore, I think this % is referring to the test accuracy (?). It also
says if they are different for two or markers then the twins are
dizygotic
(fraternal).

They tested my girls on 8 DNA markers and all eight were a match so the
probability that they are identical has a greater then 99% probability
the
report states.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"multimom4" wrote in message
news:lg7ub.173192$9E1.893856@attbi_s52...
Um ... at risk of showing my ignorance here ("btw, are your bg twins
identical?") ... is 99.9 "identical"? And if so, is 98.6 identical,
too?
And if so, where the heck is the cut-off?

--Janet
Elliot, Hanna, Connor (10/21/96)
and Holly (4/4/01)

"Kender" wrote in message
news:iaYsb.197369$Fm2.182546@attbi_s04...
My girls each had their own placentas. They also had their own
sacks.
Morgan's water broke but Megan's had to be broken. We had their DNA
tested
when they were 2.5 years old. They are 99.9% alike in DNA.
--
Erin
Morgan and Megan 2/15/97
Evan 5/14/00

"KimandJuan" wrote in message
...
I am curious.....

Are there any same sex twins that were "bi-chorial" with two
separate
placentas and "BI-amniotic" with two separate amniotic sacs, and
later
DNA
tested later and proved to be identical in this news group. I
wonder
how
common it is. What has peaked my interest is the Harvard study
that
I
mentioned earlier has offered to do a DNA test as compensation for
participating. So, it has me thinking about the girls zygosity
again.


~Kimberly
Mommy to Alexis Iliana 07/17/99 and
Emma Elidia & Aislyn Gabriela 10/01/02
come see us...
http://www.babiesonline.com/babies/a/aislynemma/

Kender wrote:

It goes on to say if the areas they test match up for at
least six or
more sites then the twins are monozygotic with a greater
then 99%
probability. Therefore, I think this % is referring to the
test
accuracy (?). It also says if they are different for two
or markers
then the twins are dizygotic (fraternal).

Our multiple birth club sent some representitives to the
first international Multiple birth conference in Australia
this year and they attended a very interesting workshop on
genetic testing. I don't recall all the details bust the
gist was the comon cheek swab they do on twins to get DNA
for sampling aren't that reliable and have a significant
error rate. I wonder if that has to do with the markers your
talking about or the method.


--
Andrea

If I can't be a good example, then I'll just have to be a
horrible warning.

Kender wrote:

It goes on to say if the areas they test match up for at
least six or
more sites then the twins are monozygotic with a greater
then 99%
probability. Therefore, I think this % is referring to the
test
accuracy (?). It also says if they are different for two
or markers
then the twins are dizygotic (fraternal).

Our multiple birth club sent some representitives to the
first international Multiple birth conference in Australia
this year and they attended a very interesting workshop on
genetic testing. I don't recall all the details bust the
gist was the comon cheek swab they do on twins to get DNA
for sampling aren't that reliable and have a significant
error rate. I wonder if that has to do with the markers your
talking about or the method.


--
Andrea

If I can't be a good example, then I'll just have to be a
horrible warning.

Subject: Zygosity
From: "Taniwha grrrl"
Date: Wed, Nov 19, 2003 4:33 AM
Message-id:

Kender wrote:

It goes on to say if the areas they test match up for at
least six or
more sites then the twins are monozygotic with a greater
then 99%
probability. Therefore, I think this % is referring to the
test
accuracy (?). It also says if they are different for two
or markers
then the twins are dizygotic (fraternal).

Our multiple birth club sent some representitives to the
first international Multiple birth conference in Australia
this year and they attended a very interesting workshop on
genetic testing. I don't recall all the details bust the
gist was the comon cheek swab they do on twins to get DNA
for sampling aren't that reliable and have a significant
error rate.

Were the errors random or was it usually fraternals being mistaken as
identicals or vice versa?


And what sort of error rate are you talking about?

Lori

Subject: Zygosity
From: "Taniwha grrrl"
Date: Wed, Nov 19, 2003 4:33 AM
Message-id:

Kender wrote:

It goes on to say if the areas they test match up for at
least six or
more sites then the twins are monozygotic with a greater
then 99%
probability. Therefore, I think this % is referring to the
test
accuracy (?). It also says if they are different for two
or markers
then the twins are dizygotic (fraternal).

Our multiple birth club sent some representitives to the
first international Multiple birth conference in Australia
this year and they attended a very interesting workshop on
genetic testing. I don't recall all the details bust the
gist was the comon cheek swab they do on twins to get DNA
for sampling aren't that reliable and have a significant
error rate.

Were the errors random or was it usually fraternals being mistaken as
identicals or vice versa?


And what sort of error rate are you talking about?

Lori