Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) trichothiodystrophy ?
    ### Response:
    Trichothiodystrophy, which is commonly called TTD, is a rare inherited condition that affects many parts of the body. The hallmark of this condition is brittle hair that is sparse and easily broken. Tests show that the hair is lacking sulfur, an element that normally gives hair its strength.
    