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Post by copperhead on Jul 29, 2012 16:57:42 GMT -5
I have been reading the thread on PHA, all are saying that for an animal to be a carrier, they must have both parents as carriers. I have a PHA carrier, her mother is not a carrier, her sire is deceased, but I think he probably was a carrier. I have had her tested twice, two different facilities and she comes back positive, so, I'm I not understanding this, or what.  |
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Post by lakeportfarms on Jul 29, 2012 17:12:01 GMT -5
Only one of the parents have to be a carrier for it to pass on the PHA gene. The sire was obviously a carrier for PHA to pass it on to your cow.
If both parents are carriers, there is a 25% probability that you'll have a PHA affected calf (lethal), a 50% chance it will also be a carrier, and a 25% chance it would be a normal calf.
If only one parent has the PHA mutation there is a 50/50 chance the calf would have it, but it is not lethal.
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Post by kansasdexters on Jul 29, 2012 17:15:21 GMT -5
Hi PJ,
If both the sire and dam are PHA-carriers, then the matings can have the following outcomes:
25% probability of being PHA-affected (the calf inherits the PHA gene from both the sire and from the dam, so the calf is homozygous for PHA). A PHA-affected calf is deformed and can be severely swollen causing problems for the cow during delivery.
50% probability of being a PHA-carrier (the calf inherits a PHA gene from either the sire or from the dam and a normal gene, so the calf is heterozygous for PHA). A PHA-carrier appears normal in every way, since the PHA gene is recessive to the normal gene and the normal gene in this gene pair performs the necessary functions of this gene.
25% probability of being PHA-free, a noncarrier (the calf inherits a normal gene from the sire and from the dam, so the calf is homozygous for the normal gene and is PHA-free).
Only one parent has to be a PHA-carrier in order to produce another PHA-carrier. A PHA-carrier that is bred to a PHA-free (non-carrier) animal can produce the following:
0% probability of being PHA-affected -- no chance of a deformed calf due to PHA
50% probability of being a PHA-carrier
50% probability of being PHA-free (non-carrier)
Patti
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Post by lakeportfarms on Jul 29, 2012 17:15:33 GMT -5
There is a thread somewhere here where Genebo shows how it is possible to do a search for the descendants of Woodmagic Wheatear using the search function of the pedigree page of the ADCA website (I think it's "F10" or something) where you type in your cow's name to see if she's a descendant. Very helpful... My guess is it will show it on the sire's side.
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Post by cddexter on Jul 29, 2012 18:12:15 GMT -5
The ADCA article uses the 'correct' scientific nomenclature, which is confusing. 'Carriers' are those with one gene. 'Affected' are those with two and thus born dead. If you think of dwarfism, there are carriers and then there are bulldogs. Use the same process with pha: there are carriers and then there are 'affected' animals, which to carry the analogy to its conclusion, you could use the unscientific term, 'waterbabies'. In the case of pha, saying you have to have two genes to be affected just means it takes both parents being carriers to ever get a dead calf. c.
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Post by lakeportfarms on Jul 29, 2012 20:47:10 GMT -5
I beat you to it Patti but your explanation was more complete, so it's a tie  |
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Post by copperhead on Jul 30, 2012 21:03:32 GMT -5
Ok, thanks. I know the sire was the carrier, I checked on that when I got her results. I mis-read the ADCA page to mean carrier means affected. Thanks to you all, it's great having this board as a resource, very knowledgable people here.
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