XYY chromosome refers to a congenital abnormality of chromosome number, which is also known as the Chao Xiong Syndrome in clinical practice. Normally, the male sex chromosome is XY and the female sex chromosome is XX. However, if the Y chromosome does not separate during the formation of the father’s spermatozoon, the spermatozoon will have two Y chromosomes, and the fertilized egg may have XYY sex chromosomes. Males with hyperandrogenic syndrome are tall and have normal or low intelligence, and some may have learning disabilities. Patients with this syndrome are usually aggressive and have a tendency toward violence. However, sexual function is normal and the vast majority of patients are fertile. One of the Y chromosomes is inactivated when sperm is produced in patients with hyperandrogenic syndrome, so the incidence of chromosomal abnormalities in their offspring is not high. Pregnant women should undergo regular prenatal checkups during pregnancy, and once a fetus is found to have a serious chromosomal abnormality, they should consult their doctor for advice and need to terminate the pregnancy if necessary.