I read this one or two (or more) decades ago, I think in Omni magazine.
It was told from the father's perspective; he's the CEO of a company that finds alien technology and is studying it.
His daughter for some reason (accident? sickness?) has to undergo an experimental treatment using their technology. It seems to be a success, but she slowly turns into one of the aliens; the dad is desperately trying to find a way to stop/reverse it.