A hairy subject!

Pili Torti or "twisted hair". The hairs are flattened, and grow with a 180 degree rotation around the long axis. They appear spangled in reflected light. One cause is Menkes kinky hair syndrome, a disorder of copper transport. Other conditions such as Bjornstad Syndrome (associated with sonsorineural deafness), Bazex Syndrome (associated with basal cell carcinomas of the face), as well as other conditions.

Cheveux incoiffables, also called "spun glass hair", results in wooly hair that is impossible to comb.

Pili annulati or "ringed hair" presents with hair that is banded in alternating dark and light rings. Hair grows normally and looks healthy.

More as I find it.