Makindo Medical Notes

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About Androgen Insensitivity Syndrome (AIS)

• Genetic Background: AIS is a condition in which an individual with an XY chromosomal pattern, genetically male, exhibits a predominantly female external phenotype. This occurs due to mutations or deletions affecting the androgen receptor gene on the X chromosome, rendering tissues insensitive to androgens.
• Pathophysiology: Without functional androgen receptors, the typical masculinization of the external genitalia does not occur. As a result, affected individuals develop female external characteristics despite having testes and producing male levels of androgens.

Clinical Features

• Secondary Sexual Characteristics: Patients typically develop normal or even enhanced breast tissue (partly due to the aromatization of androgens to estrogens in the liver), yet they often exhibit absent or minimal axillary and pubic hair.
• Reproductive Anatomy: The uterus is usually absent, and the vagina is often short and blind-ending. The gonads, which are testes in most cases, may be located in the abdomen or inguinal canal.
• Fertility and Menstrual Function: Individuals with complete AIS are infertile and do not experience menstruation.
• Family History: There may be a familial pattern, as AIS can affect other genetically male relatives who present with a similar phenotype.

Investigations

• Hormonal Profile: Laboratory tests typically reveal male-range serum androgen levels, low to normal estrogen levels, and elevated gonadotropins (LH and FSH) due to the lack of negative feedback.
• Genetic Testing: A buccal smear or full chromosomal analysis is performed to confirm the presence of an XY karyotype. In some cases, further analysis may be necessary to exclude mosaicism.
• Additional Endocrine Assays: Measurements of LH, FSH, estradiol, and testosterone help to elucidate the hormonal milieu and confirm the diagnosis.

Management

• Psychological Support: Comprehensive counseling is critical for patients and their families to address issues related to gender identity, fertility, and the psychosocial impact of the diagnosis.
• Malignancy Prevention: Since the undescended testes have an increased risk (approximately 25%) of malignant transformation (e.g., teratoma or dysgerminoma), surgical removal of the gonads is recommended after puberty.
• Surgical Management: In cases where a functional vagina is desired, reconstructive options such as vaginoplasty or progressive dilatation may be offered to create or lengthen the vaginal canal for sexual activity.
• Hormone Replacement Therapy: Estrogen supplementation is provided post-gonadectomy to promote secondary sexual characteristics, maintain breast development, and prevent osteoporosis.

Conclusion

Androgen Insensitivity Syndrome is a unique condition where genetic males present with female phenotypes due to nonfunctional androgen receptors. Clinically, AIS is characterized by normal breast development, minimal body hair, absence of a uterus, and a short, blind vagina, with testes often located in the abdomen or inguinal canal. Diagnosis relies on hormonal assays and karyotyping, while management focuses on psychological support, prophylactic gonadectomy to prevent malignancy, and hormone replacement therapy to ensure optimal long-term health outcomes.