Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Tetrasomy X ?
    ### Response:
    What causes tetrasomy X? Tetrasomy X is usually caused by a random error in the formation of an egg cell (before pregnancy). In some cases, it may be due to inheriting three X chromosomes from the mother and one X chromosome from the father. In other cases, it may be due to inheriting all four X chromosomes from the mother.
    