Symptoms and Diagnosis of Androgen Insensitivity Syndrome
Androgen insensitivity syndrome (AIS) is a rare genetic condition in which the body cannot respond properly to male sex hormones called androgens. Testosterone is the main androgen. Although a person with AIS typically has XY chromosomes, the body's cells may not respond to testosterone in the usual way.
This can affect the development of the reproductive organs and external genitalia. The condition can vary significantly from one person to another. In some cases, the body does not respond to androgens at all, while in others, it responds partially.
Understanding its symptoms and available treatment options can help individuals and families seek appropriate medical care.
What Is Androgen Insensitivity Syndrome?
Androgen insensitivity syndrome occurs when the body cannot respond normally to androgens. This usually happens because of a change in the AR gene, which provides instructions for making the androgen receptor.
The androgen receptor helps cells respond to hormones such as testosterone. When this receptor does not function properly, testosterone cannot produce its usual effects on the body's tissues.
The condition is generally associated with XY chromosomes. However, the physical development of a person with AIS can vary depending on how much the body responds to androgens.
What Causes Androgen Insensitivity Syndrome?
AIS is caused by a genetic change affecting the AR gene. This gene is located on the X chromosome and is responsible for making androgen receptors.
The condition is usually inherited in an X-linked pattern. In some cases, the genetic change may occur spontaneously rather than being inherited from a parent.
Depending on the level of androgen receptor function, AIS is generally classified into three main forms.
Types of Androgen Insensitivity Syndrome
There are three broad forms of androgen insensitivity based on how the body responds to androgens.
Complete Androgen Insensitivity Syndrome
Complete androgen insensitivity syndrome (CAIS) occurs when the body's cells cannot respond to androgens.
People with CAIS generally have XY chromosomes but develop typically female external genitalia. They have testes, which may be located inside the abdomen or in the groin. They do not usually have a uterus or ovaries.
Complete androgen insensitivity may sometimes be discovered during infancy, particularly if an inguinal hernia (a swelling in the groin area) leads to further investigation. In other cases, it may become apparent during puberty when menstruation does not begin.
Partial Androgen Insensitivity Syndrome
In partial androgen insensitivity syndrome (PAIS), the body's cells have some ability to respond to androgens, but the response is reduced.
The physical features can vary considerably. Depending on the degree of androgen response, a baby may have predominantly female, predominantly male, or genital features that do not fit typical male or female patterns.
Some individuals may have undescended testes, a smaller penis, or hypospadias.
Mild Androgen Insensitivity Syndrome
In mild AIS, the body retains a greater degree of sensitivity to androgens. The external genitalia are generally male.
The condition may become noticeable during puberty or adulthood. Some individuals may experience reduced fertility, reduced sperm production, or breast development.
Androgen Insensitivity Syndrome Symptoms
The signs of AIS vary depending on whether the condition is complete, partial, or mild.
Possible symptoms include:
- External genitalia that differ from typical male development
- Undescended testes
- Delayed or absent menstruation
- Little or no pubic or underarm hair
- Breast development during puberty
- A shorter-than-usual vagina
- Small penis or hypospadias
- Reduced sperm production
- Infertility
Not everyone with AIS experiences the same symptoms. Some people may not know they have the condition until adolescence or adulthood.
Androgen Insensitivity Syndrome in Females
The term androgen insensitivity syndrome female can be confusing because AIS is generally associated with XY chromosomes.
A person with complete AIS may have typically female external genitalia and may be raised as a girl. During puberty, breast development usually occurs because of the body's hormonal environment.
However, menstruation does not occur because there is no uterus. Pubic and underarm hair may also be sparse or absent.
A healthcare professional may investigate the cause of absent periods and discover AIS through hormone tests, chromosome testing, imaging, or genetic testing.
Androgen Insensitivity Syndrome in Males
The presentation of androgen insensitivity syndrome in males varies depending on the degree of androgen response.
Individuals with partial or mild AIS may have predominantly male external genitalia. Some may have undescended testes, hypospadias, a smaller penis, breast development during puberty, or reduced fertility.
Because the signs can vary widely, medical evaluation is important when genital development or puberty does not progress as expected.
How Is Androgen Insensitivity Syndrome Diagnosed?
Health care professionals may suspect AIS based on physical findings, delayed puberty, absent periods, or differences in genital development.
Depending on the individual's age and symptoms, diagnosis may involve:
- Physical examination
- Hormone tests
- Chromosome analysis
- Genetic testing
- Ultrasound or other imaging tests
Genetic testing can identify changes in the AR gene and may help confirm the diagnosis.
A healthcare team may include specialists such as an endocrinologist, urologist, gynaecologist, genetic counsellor and psychologist, depending on the individual's needs.
Androgen Insensitivity Syndrome Treatment
There is no single androgen insensitivity treatment suitable for everyone. Treatment is planned according to the type of AIS, age, physical development and individual healthcare needs.
Hormone Therapy
Hormone therapy may be recommended in some individuals. For example, people with CAIS who undergo gonadectomy (surgical removal of the testes) may require lifelong oestrogen replacement therapy to support bone health and maintain secondary sexual characteristics.
Hormone treatment can help support physical development and bone health when the body is no longer producing sufficient sex hormones.
Surgery
Surgery may be considered in certain situations. For example, a procedure may be recommended for undescended testes or particular genital differences.
For individuals with a shorter vagina who experience difficulties with sexual intercourse, vaginal dilation may sometimes be recommended. In selected cases, surgery may also be considered.
The timing and type of surgery should be discussed carefully with a specialist healthcare team.
Psychological Support
AIS can involve questions about physical development, fertility, relationships and personal identity. Counselling and psychological support can help individuals and families understand the condition and cope with these concerns.
Genetic counselling may also be helpful for understanding how AIS can be inherited and whether other family members could be affected.
Can Androgen Insensitivity Syndrome Be Prevented?
AIS is a genetic condition, so there is currently no known way to prevent it.
However, people with a family history of AIS can discuss genetic counselling with a healthcare professional. Genetic counselling can help families understand the inheritance pattern and available genetic testing options.
When Should You Consult a Healthcare Professional?
Healthcare professionals' advice should be sought if a child has unusual genital development or undescended testes. In adolescents, delayed puberty or the absence of menstruation may also require medical evaluation.
Early diagnosis can help healthcare professionals understand the underlying condition and discuss appropriate treatment and long-term care.
Reader information: This article is for informational purposes only and does not replace professional medical advice. AIS is a rare genetic condition requiring individualised evaluation and care. Symptoms such as differences in genital development, undescended testes, delayed puberty, or absent menstruation should be medically evaluated. Treatment, including hormone therapy, surgery, and fertility care, depends on the type of AIS and individual health needs. Always consult a qualified healthcare professional before making medical decisions.
