"I know you are still in early stages of your research, but I was just wondering if you think the method of inheritance for achondroplasia is similar to what we've discovered in humans? Is it still a possibility, or can we rule it out?"
"To save you the time typing it out for everyone, in humans:
1) Living achondroplastic dwarves are heterozygous for the mutation. The trait is dominant.
2) The majority of the time the mutation that causes achondroplasia is new, neither of the parents have the trait.
3) It has been suggested that in new mutations occur during sperm formation due to replication errors.
4) All populations are considered equally ak risk, but mutations at different locations have been discovered in different populations."
ACH (short for Achondroplasia) in humans is caused by a single base pair mutation in the FGFR3 gene. ACH is dominant and almost all of the cases whether sporadic or inherited are dominant heterozygous, this is because the dominant homozygous form (generally inherited from two dwarfs) is severely effected usually causing early death. 90% of all of the ACH cases are sporadic, which means they happen by chance and are not inherited from the parents, the other approx. 10% is inheritaed from the parents, meaning one or both of the parents are dwarfs.
This mutation occurs in oogenesis or spermatogensis, the terms used for the process the body uses for making egg and sperm, respectively. I do not know of any scientific study that has proven that the mutation only occurs in the sperm during spermatogenesis. Since it is a non-sex linked disease, and it involves a gene that both males and females carry, it has just as much chance of sporadically mutating in the female as in the male.
Mutations at different spots in the FGFR3 gene are known and they do cause different types of bone growth abnormalities. These have been shown to be some sporadic in nature as well as some mutation being familial and inherited in specific families. I am currently collaborating with a human MD and Genetic specialist at the University of Washington, (Washington the state), he studies are specialized in the dwarfisms and mutations in the FGFR3 gene.
NOW all that being said to answer your question about if it is similar to the horses, yes and no. The horses disease is inherited recessively, contrary to the ACH. There is a dwarfism in the humans that I am concentrating on right now in my lab work that is physically very smilar to the ACH look, but it is inheritaed recessively in the humans, just like the horses. There are other inherited traits in humans with AMDM that follow the minis very closely. So right now the disease AMDM is were I am looking, along with having someone else help with looking at ACH.
John
