Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Leukonychia totalis ?
    ### Response:
    What causes leukonychia totalis? Leukonychia totalis (also called total leukonychia) is thought to be due to abnormal keratinization (conversion into keratin) of the nail plate. Keratin is a protein that is a major component of the epidermis (outer layer of skin), hair, nails, and horny tissues.
    