1. Reproductive dysfunction (infertility, multiple miscarriages, malformations): At least 7-10% of couples with reproductive dysfunction such as infertility, multiple miscarriages and malformations are carriers of chromosomal abnormalities. 2, secondary sex characteristics abnormalities: (common in women) primary amenorrhea, sexual dysplasia with short stature, elbow ectropion, shield chest and slightly low intelligence, little or no pubic hair, axillary hair, low posterior hairline, sterility, etc.. These patients should consider whether they have X chromosome abnormalities, common X chromosome abnormalities are Turner’s syndrome and ring X chromosome. 3. External genital hermaphroditism (Patients who have difficulty in correctly deciding their gender based on genital appearance): Blurred differentiation of external genitalia, such as penis with hypospadias, clitoral hypertrophy in the form of penis, can be clearly diagnosed by sex chromosome examination. Gender anomalies can be divided into true hermaphroditism, pseudohermaphroditism, sex reversal syndrome, etc. a. True hermaphroditism: the internal genitalia have the characteristics of both sexes, i.e. the testes, vas deferens, ovaries and fallopian tubes exist in the body at the same time. b. Pseudohermaphroditism: It is further divided into female pseudohermaphroditism and male pseudohermaphroditism. Female pseudohermaphroditism has female internal genitalia, with uterus, ovaries and fallopian tubes, and chromosome examination is 46,XX. Male pseudohermaphroditism has male internal genitalia, i.e., gonads are testes, and chromosome karyotype is 46,XY. c. Sex reversal syndrome: i.e., chromosome karyotype is opposite to phenotype. 46,XX male, 46,XY female. 4. Congenital multiple anomalies and mental retardation: These children are characterized by multiple anomalies and mental retardation, and both the children and their parents should undergo chromosome examination. 5. Sexual abnormalities: males with tall stature, aggressive and aggressive behavior may be sex chromosome abnormalities. 6, exposure to harmful substances: radiation, chemicals, viruses, etc. can cause chromosome breakage, resulting in aberrations, which can cause some corresponding diseases, such as tumors, if they occur in somatic cells. If the aberrations occur in the germ cells, the genetic effects will affect the offspring and cause miscarriages, stillbirths and deformed children. 7, premarital chromosome examination: can find normal performance of abnormal chromosome carriers, such as chromosome balanced translocation, inversion, chromosome balanced translocation and inversion because the gene is not lost and the phenotype is normal, but very easy to cause miscarriage, abnormal fetus, stillbirth, blind birth will cause the birth rate of abnormal children increased; can also find phenotypically normal sex chromosome abnormalities, these patients can be manifested as sexual dysfunction, no These patients may show sexual dysfunction, no fertility, etc.