TFS, first reported by Steglehner in 1817, is also known as androgen insensitivity syndrome, Goldberg-Maxwell’s syndrome, and Morris syndrome. The population prevalence is 1:20,000-1:60,000, which corresponds to 5% of all sexual differentiation disorders. (1) Pathogenesis of TFS 70% of TFS are X-linked recessive disorders, which are passed on to offspring through female carriers, with 50% of female offspring being carriers and 50% of male offspring having the disease. Another 30% of TFS cases may be associated with random mutations in the AR gene on the X chromosome. In our group, we observed 12 cases with a family history consistent with an X-recessive disorder, and another 5 cases with no apparent family history. (2) Mechanism of TFS internal genitalia The karyotype of TFS patients is 46,XY, and the short arm of Y chromosome has testis determine gene (TDG), which causes the gonads to develop into testes and secrete testosterone and Mullerian inhibiting hormone (MIH). MIH inhibits the development of Mullerian ducts and prevents the formation of uterus, fallopian tubes and upper 1 /3 of vagina. /MIH inhibits the development of the Mullerian ducts and prevents the formation of the uterus, fallopian tubes and upper 1/3 of the vagina. In our group, 17 patients had no uterus and fallopian tubes, and the vagina was blind-ended. Four of them had a short vagina and underwent vaginoplasty before marriage due to unsatisfactory sexual life. AR is a protein, and the gene that determines this receptor is on the long arm of X chromosome (Xq11-q12) at the human androgen receptor gene (Tfm locus.) TFS patients have mutations in the Tfm gene, and there is no male allele, so small changes will affect the formation of AR in target cells, so that androgens cannot bind to the receptor and cannot exert biological effects, thus affecting the patients’ development toward masculinity. As a result, the mesonephric duct cannot develop into epididymis, vas deferens and seminal vesicles. In TFS patients with defective AR, androgens do not work and the descent of the testes is restricted, resulting in cryptorchidism. What is particularly significant is that the cryptorchidism in this group of cases shows that the cryptorchidism of complete TFS is located in the abdominal cavity, which may be related to the complete failure of androgens to exert biological effects. (3) Mechanism of the development of external genitalia and secondary sexual characteristics in TFS More than 200 kinds of mutations in the Tfm locus have been found, and according to the degree of AR deletion, the effect of androgens is also missing to different degrees. Due to normal estrogen receptors in the body, testosterone can be converted to estrogen by the action of aromatase, causing the secondary sexual characteristics to develop toward a female phenotype with a female appearance, and the breasts develop into a female phenotype at puberty. The vulva and the lower 2/3 of the vagina are unable to function due to the lack of AR, so they naturally develop towards femininity, forming short blind ends of the vagina, labia majora and labia minora, and clitoris. The growth of pubic and axillary hairs depends on androgens. In the complete type, pubic and axillary hairs are sparse or absent because androgens do not work. The enlarged clitoris suggests the influence of elevated androgens, which is mostly seen in the incomplete type. All 17 cases in this group were consistent with the above characteristics. (4) Endocrine alteration mechanism of TFS The blood testosterone of TFS patients at puberty should be in the normal male range or higher than the normal male level, and the estrogen measurement is equivalent to the follicular phase level, and the LH and FSH are elevated; the reason for the elevated LH may be due to the negative feedback effect on the pituitary gland weakened by the lack of estrogen in the body. In the past literature, it was thought that there might not be much difference between complete and incomplete endocrine types, mainly because of the difference in the sensitivity of AR in vivo, but this study found that the blood testosterone of both types was significantly higher than the maximum limit of 3 nmol/L in normal women, and the testosterone value of complete type was significantly higher than that of incomplete type, which was statistically different, the reason for which needs to be further explored. 2. The principles of treatment of TFS should mainly focus on two aspects: gender selection and gonadal treatment. The testes should not be removed in child patients, only vulvoplasty should be done, and regular postoperative review should be done, and then bilateral testes should be removed in adulthood. (1) Sex selection In the process of gender role formation, the dependent sex is much more important than the biological sex (external genitalia, dominant hormones, gonadal structures). In addition, changing the rearing sex after infancy can lead to serious psychiatric consequences; therefore, changing sex after infancy by changing the external genitalia to match the gonadal structures is rarely recommended. Instead, the physician should try to help the patient adjust to the gender role that has been decided upon. Regardless of the time of treatment (the earlier the better, of course), the gynecologist should reconstruct the external genitalia to conform to the rearing sex, and any kind of opposite sexual structure that may be detrimental to the patient in the future should be removed. The complete patient has purely female secondary sexual characteristics and a female psychosexual orientation, but the karyotype is 46, XY, and the gonads are also completely male. The patient has been raised as a girl since childhood, has well-developed breasts at puberty, and is completely feminine in body shape, fat distribution, and appearance. The child and her parents should be gradually informed of this complex situation. at the age of 8 years, it is sufficient to reassure the child that she is a normal, healthy girl who will grow up like her peers. When her breasts begin to develop, she should be told that she does not have a uterus and will not have menstruation. When she reaches puberty, she should be told in advance that she will need follow-up surgery to remove her cryptorchid, vaginal dilation, hormone replacement, and a detailed discussion of her infertility. Once she has fully understood her fertility and sexuality, she should be informed that her genotype and phenotype are incompatible and emphasized that her sex is assigned by phenotype, not genotype. Incomplete types are partially sensitive to exogenous androgens and may also be raised as masculine. (2) Reconstruction of the external genitalia Most complete types do not require vulvoplasty, while incomplete types may require vulvoplasty. The purpose of vulvoplasty is to keep the patient in a good psychological state and more suitable for the female physiology, so it is important to emphasize that female external genital reconstruction must be performed as early as possible in order to strengthen the desired psychological, social and gender characteristics of the patient and also to make it easier for the parents to face the facts. Sometimes reconstructive surgery of the external genitalia can be performed in the neonatal period. In our group, three patients underwent “vulvoplasty and partial excision of the enlarged clitoris” at the ages of 13, 15, and 16 years, respectively. (3) Treatment of ectopic testes The purpose of treatment of ectopic testes differs between complete and incomplete types. The complete type is mainly to prevent testicular malignancy, while the incomplete type is mainly to prevent the development of secondary sexual characteristics towards masculinity. Although ectopic testes are prone to germ cell tumors (asexual cell tumors, seminoma, and gonoblastoma), Speroff et al. proposed that testicular malignancy in the complete type rarely occurs before puberty and that orchiectomy should be performed after the age of 16 to 18 years to ensure that endogenous hormones can smoothly pass through puberty and ensure breast development, body growth, and feminization. In this investigation, there was one complete case of testicular support-mesenchymal cell tumor at the age of 18 years. Patients with incomplete TFS develop masculinization at puberty and should have their testes removed before puberty, along with the enlarged clitoris, to prevent the progression to masculinity, so that the negative effects of the hermaphroditic phenotype can be prevented. In one case in this group, the testicles were removed at the age of 13 due to the development of an enlarged clitoris. (4) Problems with vaginoplasty The blind end of the vagina in TFS varies in length, some are just a shallow fossa, but the vagina can be successfully dilated with a vaginal dilator, and if this fails, vaginoplasty can be performed before marriage. If dilation fails, vaginoplasty can be performed before marriage. If there is no sexual life, vaginoplasty should be followed by regular vaginal dilatation. In our group, 4 out of 17 patients underwent vaginoplasty before marriage, and all of them were satisfied with their sexual life after the operation. (5) Problems after orchiectomy After orchiectomy, the sex hormone in the body decreases significantly, and small doses of estrogen must be taken continuously to maintain female secondary sexual characteristics. All 17 patients in our group were treated with Bemelia 0.625mg/d after orchiectomy, and all of them had no obvious side effects during the follow-up period of 6 months to 5 years. Female secondary sexual characteristics were maintained and strengthened, while male secondary sexual characteristics were curbed.