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Babies with androgen insensitivity syndrome (AIS) will be genetically male, but will either have female genitals or an appearance between male and female genitalia.

There are 2 main types of AIS, which affect people in different ways:

  • complete androgen insensitivity (CAIS)
  • partial androgen insensitivity (PAIS)

Read more about these 2 types of AIS.

Complete androgen insensitivity syndrome

CAIS isn't usually obvious from birth, as affected babies have female genitals – including a vagina and labia (folds of skin either side of the vaginal opening) – and are raised as girls.

They'll also have undescended testicles, but this will usually go unnoticed unless they cause a hernia (where they push through a weakness in the surrounding tissue) or swelling in the labia.

The first obvious symptoms often don't appear until puberty, which starts at around the age of 11 or 12.

When a girl with CAIS reaches puberty, she will:

  • not start having periods
  • develop little or no pubic and underarm hair
  • develop breasts and have growth spurts as normal, although she may end up slightly taller than usual for a girl

Girls with CAIS don't have a womb or ovaries, so are unable to get pregnant. Their vagina will also be shorter than normal, which may make having sex difficult.

Partial androgen insensitivity syndrome

The development of children with partial androgen insensitivity syndrome (PAIS) can vary.

In many cases, the genitalia are between male and female from birth. For example, affected babies may have:

  • a very small penis or an enlarged clitoris (the sexual organ that helps women reach sexual climax)
  • partially undescended testicles
  • hypospadias – where the hole through which urine passes out of the body is on the underside of the penis, rather than at the end

Children with PAIS are usually raised as boys, although they may experience poor penis development during puberty and develop small breasts. Most children with PAIS raised as boys will be infertile.

Some children with PAIS are raised as girls. Like those with CAIS, girls with PAIS don't have a womb or ovaries and won't be able to get pregnant.