I am currently working on a post-apocalyptic world where roughly 90% of humanity get infected by HDD (Human Degenerative Disease). HDD causes the human brain, gland and tissues to change quite dramatically. Reducing the majority of the infected to a feral state in which they are no longer sapient, but can be trained (with effort) similarly to gorillas, chimpanzees and dogs. The infected breed true among themselves, seem to have no memories of their past lives, and over the past 30 years have propagated a great deal. An immune or uninfected person who breeds with one of these new ferals has a 75% chance of producing non-feral offspring.
However, many of the infected bred with other infected and as a result the disease developed into several new strains. One affecting the endocrine system most strongly, one affecting the bodies tissues (musculature,skin and tendons most),one overhauling the neurological system in new and alien ways (maybe developing similar structures to an electric eel?) and, lastly, one that leaves the sapience intact but creates non-linear mutations in some to all systems of the body.
I am wondering what kinds of human sub-species could result specifically from the mutating tissue strain? I imagine their size and musculature would be affected,but surely more could occur. I am thinking the development of more predatory features and perhaps natural camouflage. But I want more info on how this could occur if at all.
The idea is this is a massive spontaneous mutation that occurs following the outbreak of an airborne retrovirus which at first seemed harmless. Ideally I need ideas for plausible changes that could occur in at least one of the strains above in humans.
Thanks in advance. Just let me know if this needs to be narrowed down further.