The normal human body contains 23 pairs of chromosomes, which are the important genetic material of the human body. If there are chromosome abnormalities, patients will also have various diseases, common chromosome diseases can be divided into the following categories: first, chromosome number abnormalities, such as the most common trisomy 21, refers to the patient’s chromosome 21 pairs of chromosomes appear three, the main clinical manifestations of mental retardation, developmental delay, similar abnormalities also include trisomy 18, trisomy 13, also Similar abnormalities include trisomy 18, trisomy 13, and sex chromosome abnormalities. Second, chromosomal fragment abnormalities, such as abnormalities on the short arm of the ninth chromosome pair, have clinical manifestations of small head, wide eye spacing, small eyes, and dysplasia, and most die in early childhood. Screening for chromosomes can detect common basic chromosomal abnormalities, which are usually untreatable and therefore early detection is very important for eugenics.