Genetic diseases are diseases determined by genetic factors and are diseases caused by changes in genetic material, rather than as the name implies, genetic diseases are all diseases that must run in families. Modern genetics classifies human genetic diseases into five categories: chromosomal diseases, monogenic diseases, polygenic diseases, somatic genetic diseases, and mitochondrial genetic diseases. Chromosomal disorders are a type of genetic disease. There are 23 pairs of chromosomes in a normal human being, one from the father and one from the mother, of which the sex chromosomes determine human sex, X chromosomes in females and Y chromosomes in males, so there are 24 types of chromosomes in humans. When abnormalities occur in the structure or number of these chromosomes, they can cause chromosomal disorders. Among the chromosomal disorders, the most common one is Down syndrome, also known as trisomy 21, congenital stupidity. Therefore, Down’s syndrome screening is usually performed routinely during pregnancy, and further prenatal diagnosis is required for high-risk pregnancies.