I was just wondering…every once in a while these days, one hears about some lab animal that has been genetically modified to carry some human genes, like pigs that have been engineered to produce a human blood enzyme that hemophiliacs lack. Now, I don’t want to start a debate over Genetic Research, nor do I want to invite any…“raunchy” suggestions about the scientists, but I’d like to know…Where or Who do they get the human DNA from to engineer into the animal in the first place?
Its probably easier to synthesize a given gene based on its known sequence (sequenced from a wide variety of people) than it is to collect a piece of DNA from a human and transfer it. From human to human - and indeed, from species to species - gene sequences vary very little, and so once an average sequence of a gene is known, one can synthesize it from scratch nucelotides and slice it into the DNA of a cell.
I imagine they’d synthesize their own to ensure everyone’s using the same genetic material in each run of the experiment. You can’t have more than one uncontrolled condition if the results of the experiment are to make sense.
In some cases the DNA doners are people with a pronounced form of genetic defect. For example, there’s a strain of mice genetically modified with a chromosome thought responsible for overian cancer – “The doner was a woman with a long family history of the disease identified only as A-122”.
In other cases the doctors simply use their own DNA. I remember reading about a lab technician who was rather proud of the fact that his genes were used in a popular strain of insulin producing microbes.