Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Mosaic trisomy 9 ?
    ### Response:
    How is mosaic trisomy 9 diagnosed? In some cases, mosaic trisomy 9 is diagnosed before birth. A pregnancy ultrasound may reveal signs and symptoms that are suggestive of a chromosomal or developmental disorder. Additional tests, such as chorionic villus sampling (CVS) or an amniocentesis, may be offered to further investigate these features.
    