Androgen insensitivity syndrome (AIS) is a rare condition that affects the development of a child's genitals and reproductive organs.
A child born with AIS is genetically male, but the external appearance of their genitals may be female or somewhere between male and female.
Someone with AIS may benefit from psychological support, and in some cases may have treatment to alter the appearance of their genitals.
Most people born with the condition are unable to have children, but they'll otherwise be perfectly healthy and able to lead a normal life.
What causes AIS?
AIS is caused by a genetic fault that's usually passed on to a child by their mother.
This genetic fault means that, despite being genetically male, the body doesn't respond to testosterone (the male sex hormone) properly and male sexual development doesn't happen as normal.
This means the penis doesn't form or is underdeveloped. The child's genitals may appear female, or between male and female, but they don't have a womb or ovaries and have fully or partially undescended testicles.
Women who carry the genetic fault won't have AIS themselves, but there's a one in four chance each child they have will be born with the condition.
Read more about the causes of AIS.
Types of AIS
There are two main types of AIS, which are determined by how much the body is able to use testosterone. These are:
- complete androgen insensitivity syndrome (CAIS) – where testosterone has no effect on sexual development, so the genitals are entirely female
- partial androgen insensitivity syndrome (PAIS) – where testosterone still has some effect on sexual development, so the genitals are often between male and female
PAIS is usually noticed at birth because the genitals appear different.
CAIS can be more difficult to spot, as the genitals usually look normal for a girl. It's often not diagnosed until puberty, when periods don't start and pubic and underarm hair doesn't develop.
Read more about the symptoms of AIS and diagnosing AIS.
Living with AIS
Children with AIS and their parents are supported by a team of specialists, who will offer ongoing care and support. They will help you decide whether to raise your child as a girl or a boy while they're still very young.
Most children with CAIS are raised as girls, while those with PAIS can be brought up either as girls or boys. It's up to you as a parent, with help from specialists, to decide what you think is in the best interests of your child.
Once you've decided, you can learn about the treatments available that can help make your child's body look more consistent with the chosen gender and help them develop more naturally.
This may involve surgery to alter the appearance or function of their genitals, and hormone treatment to encourage female or male development during puberty.
Read more about how AIS is treated.
Support and advice
You and your child will be offered psychological support to help you understand and cope with the diagnosis of AIS. Children may not need this while they're very young, but they usually do as they get older.
You'll be given advice about how and when to discuss the condition with your child.
You may also find it helpful to get in touch with a support group, such as the Androgen Insensitivity Syndrome Support Group (AISSG) and DSD Families.
Information about your child
If your child has AIS, your clinical team will pass information about him or her on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.
Find out more about the register.