Androgen Insensitivity Syndrome

Overview

Androgen insensitivity syndrome (AIS) is a genetic condition that affects sexual development. It happens when a person has XY chromosomes (usually male) but their body cannot respond to male hormones called androgens. Depending on how much the body can respond, a person may develop female features, male features, or something in between.

AIS is rare. Experts estimate it affects about 1 in 20,000 to 1 in 99,000 people assigned female at birth.

AIS affects people with XY chromosomes. It can be passed down from a mother who carries the genetic change, or it can happen with no family history.

Symptoms

Common symptoms

• In complete AIS, there are often no visible symptoms until puberty, when a girl does not start having periods.
• Absent or sparse underarm and pubic hair.
• Infertility.
• Taller than average height.

Symptoms in children

• A swelling in the groin caused by an undescended testicle (may be found during a hernia repair).
• Ambiguous genitalia at birth (genitals that look different from typical male or female), especially in partial AIS.
• In a child with XY chromosomes, the testicles may not be felt in the scrotum.

Symptoms in older adults

• Older adults may have no specific AIS symptoms, but they may face bone thinning (osteoporosis) if their gonads were removed and they did not receive hormone replacement therapy.
• Some people experience emotional challenges related to identity, relationships, and body image.

Causes

Main causes

• A change (mutation) in the androgen receptor gene, which tells the body how to recognize and use androgens.
• This genetic change makes the body's cells partially or completely unable to respond to androgens.
• AIS is usually inherited from the mother, who may carry the changed gene without having symptoms, but it can also happen as a new change in the child.

Risk factors

• Having a family history of AIS or related differences in sex development.
• A mother who is a carrier of the androgen receptor gene change has a 50% chance of passing it to each child with XY chromosomes.

When to see a doctor

See a doctor urgently if:

• If you or your child has sudden, severe groin or abdominal pain, or a swollen, tender groin, go to the nearest emergency department or call your local emergency number.

Book a routine appointment if:

• If your child has not started menstruation by age 15 (in someone with a typical female body).
• If you notice your child has ambiguous genitalia or a groin lump that concerns you.
• If you have questions about fertility, sexual development, or your child's growth.

Diagnosis

Doctors diagnose AIS after a careful physical exam, blood tests to check chromosomes and hormone levels, and genetic testing to look for changes in the androgen receptor gene. Sometimes AIS is found when a teenager does not start periods or when hernia surgery reveals a testicle.

Tests that may be done

• Chromosome analysis (a blood test to look at your chromosomes).
• Hormone blood tests, including testosterone and other sex hormones.
• Ultrasound or MRI scans to look inside the body for internal testes, a uterus, or other organs.
• Genetic testing to confirm changes in the androgen receptor gene.

What to expect at your appointment

Diagnosis can take time and may involve several specialists, such as a paediatrician, an endocrinologist (hormone specialist), a urologist, a gynaecologist, and a genetic counsellor. They will explain each test and guide you through the findings. You can ask questions at any time and take time to think about the information.

Treatment

Treatment for AIS focuses on helping you or your child stay healthy and feel supported, not on 'correcting' the condition. The right approach depends on the type of AIS, your age, and your own preferences. A team of specialists will meet with you to discuss all options.

Self-care at home

• Learn about AIS from reliable sources so you can make informed choices.
• Write down any questions and bring them to medical appointments.
• Connect with support groups to hear from other people and families affected by AIS.
• Keep a record of your symptoms, treatments, and any concerns you have.

Medical treatments

Hormone replacement therapy (HRT) is sometimes recommended after puberty or if the gonads (testes) are removed, to support bone strength, heart health, and overall well-being. The decision to use HRT is individual and should be made with an endocrinologist. Surgery may be an option to remove internal testes because they carry a small risk of cancer later in life, or to address genital differences. Surgery is never urgent except in emergencies like testicular torsion, and decisions are made together with the family and the medical team.

When is surgery considered?

Surgery is not always needed. In complete AIS, removing the internal testes is often considered during or after puberty, because the risk of cancer rises after that time. In partial AIS, surgery may be discussed to make the appearance of the genitals more typical, but many experts recommend waiting until the child is old enough to take part in the decision.

Living with this condition

Most people with AIS live healthy, full lives. You may need regular check-ups with a specialist, especially if you have had your gonads removed or are taking hormone replacement therapy. These check-ups help manage your bone health and make sure your hormone levels are balanced.

Lifestyle tips

• Stay active with regular physical activity you enjoy.
• Do not smoke, and limit alcohol to protect bone and heart health.
• Keep up with routine medical appointments and screenings.
• Build a network of trusted friends, family, or counsellors who understand your story.

Diet and exercise

A balanced diet rich in calcium and vitamin D is important for bone health. Foods like dairy products, leafy greens, tofu, and fortified cereals can help. Weight-bearing exercises such as walking, jogging, dancing, or resistance training also help keep bones strong. Ask your doctor whether you need supplements or a nutrition review.

Mental health and emotional wellbeing

Growing up with AIS can bring up complex feelings about identity, body image, close relationships, and self-worth. It is completely normal to feel anxiety, sadness, or confusion. Talking with a mental health professional who understands differences in sex development can be very helpful. If you ever feel in crisis or have thoughts of self-harm, please reach out for immediate support — you are deserving of care.

Prevention

AIS cannot be prevented because it is a genetic condition present from conception. If you have a family history of AIS and are considering pregnancy, you can talk to a genetic counsellor about your options and what testing might be available.

Vaccines

There is no vaccine for AIS. It is not an infection.

Screening programmes

If there is a family history, genetic testing before or during pregnancy may be discussed with a genetic counsellor. This is entirely optional and personal.

Complications

If left untreated

• Small risk of cancer in the internal testes if they are not removed after puberty.
• Low bone density and osteoporosis if hormone replacement is not used after gonadectomy.
• Infertility is usual with complete AIS.
• Psychological distress or identity concerns may arise without proper emotional support.

Long-term outlook

With the right medical follow-up, hormone therapy as needed, and a strong support network, people with AIS generally enjoy good health and a normal lifespan. Many people pursue fulfilling lives, careers, and relationships. Some choose to become parents through adoption, fostering, or donor eggs. There is every reason to feel hopeful about your future.

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