???? ??? ?? ?? ? ????? ? ?? ??? ?? ???? ??? ??? ? ??? ? ??? ? ?? ? ??? ??? ??????.Trichothiodystrophy, generally termed TTD, is actually a rare inherited situation that has an effect on several aspects of your body. The hallmark of this issue is hair which is sparse and simply broken. [from MedlinePlus Genetics]Persons with PNH are at greater risk