Good Labor Day all-
You may remember the notomelia (polymelia) description from earlier. The mutation has been identified and commercial tests are becoming available. Originally it was felt that a large number of homozygous embryos/feti were aborted in the first 2 trimesters because the number of animals with polymelia was less than expected given the number of carrier animals. While this still may be true there is another twist.
Angus Australia (http://www.angusaustralia.com.au/component/content/article/8-front-page-news/1330-update-developmental-duplication-29.html) reports that there have been some NORMAL (phenotypically normal) cattle that are homozygous for the DD mutation.
So of the 5459 animals that have been genotyped, 37 are HOMOZYGOUS BUT NORMAL. This is unexpected and there are an excess of heterozygotes and deficiency of homozygotes - mathematically there should be (one would expect) 73 homozygotes.
What this means is that in this disorder there is incomplete penetrance. There are lots of potential explanations of incomplete penetrance. Dr B and BR are trying to find out why but in order to do that we NEED MORE SAMPLES - more polymelia samples and samples from other animals that have external features of duplication such as the conjoined twins and animals with extra things like skin flaps, etc..
Apparently there have been some number (8 to 10) of calves with polymelia "reported" recently but NO samples - step up to the plate - with fall calving around the corner keep your eyes open for extra legs and extra stuff - we need samples
Ideal samples are purple top tube of blood for calves that are alive and ear notch for those that are not, pictures are good too - DO NOT BE AN OSTRICH - help us figure out why/how/etc there is such a wide variation in the phenotypic expression of this disorder
As always your cooperation is greatly appreciated
You may remember the notomelia (polymelia) description from earlier. The mutation has been identified and commercial tests are becoming available. Originally it was felt that a large number of homozygous embryos/feti were aborted in the first 2 trimesters because the number of animals with polymelia was less than expected given the number of carrier animals. While this still may be true there is another twist.
Angus Australia (http://www.angusaustralia.com.au/component/content/article/8-front-page-news/1330-update-developmental-duplication-29.html) reports that there have been some NORMAL (phenotypically normal) cattle that are homozygous for the DD mutation.
So of the 5459 animals that have been genotyped, 37 are HOMOZYGOUS BUT NORMAL. This is unexpected and there are an excess of heterozygotes and deficiency of homozygotes - mathematically there should be (one would expect) 73 homozygotes.
What this means is that in this disorder there is incomplete penetrance. There are lots of potential explanations of incomplete penetrance. Dr B and BR are trying to find out why but in order to do that we NEED MORE SAMPLES - more polymelia samples and samples from other animals that have external features of duplication such as the conjoined twins and animals with extra things like skin flaps, etc..
Apparently there have been some number (8 to 10) of calves with polymelia "reported" recently but NO samples - step up to the plate - with fall calving around the corner keep your eyes open for extra legs and extra stuff - we need samples
Ideal samples are purple top tube of blood for calves that are alive and ear notch for those that are not, pictures are good too - DO NOT BE AN OSTRICH - help us figure out why/how/etc there is such a wide variation in the phenotypic expression of this disorder
As always your cooperation is greatly appreciated
