[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Androgen insensitivity syndrome [Conditions](https://durgical.com/en/conditions/) · [Endocrinology](https://durgical.com/en/conditions/) # Androgen insensitivity syndrome A genetic condition in which a person with XY chromosomes and testes does not respond to male hormones, so the body develops partly or fully female. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Testes](https://durgical.com/en/anatomy/testis/) - [Inguinal canal](https://durgical.com/en/anatomy/inguinal-canal/) - [Spermatic cord](https://durgical.com/en/anatomy/spermatic-cord/) - [Scrotum](https://durgical.com/en/anatomy/scrotum/) - [Inguinal ligament](https://durgical.com/en/anatomy/inguinal-ligament/) ## Why it happens - [Mendelian inheritance: autosomal dominant, recessive and X-linked](https://durgical.com/en/general-pathology/mendelian-inheritance-autosomal-dominant-recessive-and-x-linked/) - [Sex determination and differentiation](https://durgical.com/en/physiology/sex-determination-and-differentiation/) - [Testosterone and its actions](https://durgical.com/en/physiology/testosterone-and-its-actions/) - [Nuclear receptors](https://durgical.com/en/biochemistry/topics/nuclear-receptors/) ## What it is An X-linked difference of sex development in which a 46,XY person with testes cannot respond normally to androgens because the androgen receptor is defective. In the complete form the external genitalia are female and there is no uterus; in partial and mild forms the appearance ranges from atypical genitalia to a male phenotype with poor virilisation or infertility. ## Who gets it The complete form affects roughly 2 to 5 per 100,000 people raised as girls; the partial form is at least as frequent and the mild form is rarer. It occurs in all populations, including Colombia, where cases are managed by paediatric endocrinology and multidisciplinary sex-development teams. ## Causes - Variants in the AR gene on the X chromosome, which encodes the androgen receptor - X-linked recessive inheritance through carrier mothers in about 70% of cases - New (de novo) variants in about 30% ## Risk factors - Family history of the condition in maternal relatives (siblings, maternal aunts or cousins) - Mother known to carry an AR variant ## Pathophysiology The testes form normally and secrete anti-Müllerian hormone, so the uterus, tubes and upper vagina regress. Testosterone is produced but cannot act, so Wolffian structures and male external genitalia fail to develop and the vagina is short and blind-ending. At puberty, testosterone rises and is converted to oestradiol, producing breast development, while pubic and axillary hair stay sparse. Testosterone and LH are normal to high because the [hypothalamus](https://durgical.com/en/anatomy/hypothalamus/) and pituitary are also resistant. ## Classification - Complete (CAIS): female external genitalia, no uterus, absent or sparse body hair - Partial (PAIS): atypical genitalia (from clitoromegaly to hypospadias with micropenis) - Mild (MAIS): male genitalia with gynaecomastia, poor virilisation or infertility ## Symptoms and signs - Primary amenorrhoea in an adolescent girl with normal breast development - Sparse or absent pubic and axillary hair - Inguinal hernia or labial swelling containing a testis in a girl - Short blind-ending vagina and no palpable uterus - Atypical genitalia at birth in partial forms ## Red flags - Bilateral inguinal hernias in a phenotypic girl: check karyotype before or at surgery - New mass or pain in a retained gonad (possible germ cell tumour) - Psychological distress about diagnosis or identity: refer for specialised support ## Diagnosis **Clinical** Primary amenorrhoea with breast development but scant sexual hair, or a [testis](https://durgical.com/en/anatomy/testis/) found during hernia repair; examination of the external genitalia and [vagina](https://durgical.com/en/anatomy/vagina/). **Tests** Karyotype 46,XY. Testosterone in the male range or higher with normal or high LH; normal or high anti-Müllerian hormone, showing functioning testes. AR gene testing confirms the diagnosis and allows carrier testing of female relatives. Normal testosterone-to-dihydrotestosterone ratio helps separate it from 5-alpha-reductase deficiency. **Imaging** Pelvic ultrasound or MRI shows no uterus and locates the testes in the [abdomen](https://durgical.com/en/anatomy/region/abdomen/), [inguinal canal](https://durgical.com/en/anatomy/inguinal-canal/) or labia. ## Differential diagnosis - Müllerian agenesis (MRKH syndrome): 46,XX, normal pubic hair, normal [ovaries](https://durgical.com/en/anatomy/ovary/) - 5-alpha-reductase deficiency - Complete gonadal dysgenesis (Swyer syndrome): 46,XY with a uterus - Leydig cell hypoplasia and testosterone biosynthesis defects - Congenital adrenal hyperplasia in a 46,XX infant with atypical genitalia ## Goal of treatment Confirm the diagnosis with a multidisciplinary team, disclose it honestly and supportively, decide on the timing of gonadectomy against tumour risk, keep sex hormones adequate for bone health and support sexual function and identity. ## Treatment **Surgical** Gonadectomy, often deferred until after spontaneous breast development in the complete form because the tumour risk is low; earlier in partial forms with higher risk. Hernia repair when needed. **Medical** Oestrogen replacement after gonadectomy to maintain female characteristics and bone mass; in partial forms raised male, androgen therapy may be considered. **Conservative** Vaginal dilation therapy, preferably started when the person chooses, to lengthen a short vagina; surgery is reserved for failure. **Conservative** Psychological support, genetic counselling of the family and carrier testing of female relatives. **Follow-up** Bone density monitoring; surveillance of retained gonads by examination and imaging. ## Complications - Germ cell tumour in retained testes (low in the complete form, higher in partial forms) - Low bone mineral density, especially without hormone replacement - Infertility - Psychological distress and difficulties with disclosure - Recurrent inguinal hernia ## Prognosis Life expectancy is normal. Long-term wellbeing depends on careful disclosure, adequate hormone replacement for bone health and access to experienced multidisciplinary care. ## Test yourself Think of the answer, then tap the question to see it. ## An adolescent girl has primary amenorrhoea, normal breasts, scant pubic hair and no uterus. Which karyotype is expected? 46,XY (complete androgen insensitivity syndrome). ## Why is there no uterus in complete androgen insensitivity? The testes secrete anti-Müllerian hormone, which makes the Müllerian ducts regress. ## Why do breasts develop at puberty in complete androgen insensitivity? High testosterone is converted to oestradiol by aromatase, and the oestrogen acts unopposed. ## How is androgen insensitivity distinguished from Müllerian agenesis? Müllerian agenesis is 46,XX with ovaries and normal pubic hair; androgen insensitivity is 46,XY with testes and scant hair. ## What is the inheritance pattern of androgen insensitivity syndrome? X-linked recessive, through variants in the androgen receptor (AR) gene. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/androgen-insensitivity-syndrome/) ## Related conditions - [Inguinal hernia](https://durgical.com/en/conditions/inguinal-hernia/) - [Müllerian anomalies (MRKH, septate uterus, imperforate hymen)](https://durgical.com/en/conditions/mullerian-anomalies/) - [Turner syndrome](https://durgical.com/en/conditions/turner-syndrome/) - [Klinefelter syndrome (47,XXY)](https://durgical.com/en/conditions/klinefelter-syndrome/) - [Congenital adrenal hyperplasia due to 21-hydroxylase deficiency](https://durgical.com/en/conditions/congenital-adrenal-hyperplasia-due-to-21-hydroxylase-deficiency/) - [Testicular cancer](https://durgical.com/en/conditions/testicular-cancer/) - [Gynaecomastia](https://durgical.com/en/conditions/gynaecomastia/) - [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/) - [Gender dysphoria](https://durgical.com/en/conditions/gender-dysphoria/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Androgen insensitivity syndrome: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/androgen-insensitivity-syndrome/) (MedlinePlus Genetics (U.S. National Library of Medicine), 2025). [← All conditions](https://durgical.com/en/conditions/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/conditions/androgen-insensitivity-syndrome/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/androgen-insensitivity-syndrome/