In the first 2 to 3 months of pregnancy, all babies have the same genitals. As a baby grows inside the womb, male or female genitals develop depending on the pair of sex chromosomes from the parents. It also depends on the levels of androgens. In a baby with XY chromosomes, high levels of androgens are made in the testes. This baby will develop male genitals. In a baby with XX chromosomes, there are no testes and the levels of androgens are very low. This baby will develop female genitals. In PAIS, there is a change in the gene that helps the body recognize and use male hormones properly. This leads to problems with the development of the male sex organs. At birth, the baby may have ambiguous genitals, which leads to confusion over the baby's sex.
The syndrome is passed down through families (inherited). People with two X chromosomes are not affected if only one copy of the X chromosome carries the genetic mutation. Males who inherit the gene from their mothers will have the condition. There is a 50% chance that a male child of a mother with the gene will be affected. Every female child has a 50% chance of carrying the gene. Family history is important in determining risk factors of PAIS.
Partial androgen insensitivity syndrome (PAIS) is a disease that occurs in children when their body can't respond the right way to the male sex hormones (androgens). Testosterone is a male sex hormone.
This disorder is a type of androgen insensitivity syndrome.
Exams and Tests
The health care provider will perform a physical exam.
Tests may include:
Androgens are most important during early development in the womb. People with PAIS can have a normal lifespan and be totally healthy, but they may have difficulty conceiving a child. In the most severe cases, boys with outer female genitals or an extremely small penis may have psychological or emotional problems.
Children with PAIS and their parents may benefit from counseling and receiving care from a health care team that includes different specialists.
Prenatal testing is available. People with a family history of PAIS should consider genetic counseling.
People with PAIS may have both male and female physical characteristics. These may include:
- Abnormal male genitals, such as the urethra being on the underside of the penis, small penis, small scrotum (with a line down the middle or incompletely closed), or undescended testicles.
- Breast development in males at time of puberty. Decreased body hair and beard, but normal pubic and armpit hair
- Sexual dysfunction and infertility
Infants with PAIS may be assigned a gender depending on the extent of genital ambiguity. However, gender assignment is a complex issue and must be considered carefully. Possible treatments for PAIS include:
- For those assigned as males, surgery may be done to reduce breasts, repair undescended testicles, or reshape the penis. They may also receive androgens to help facial hair grow and deepen the voice.
- For those assigned as females, surgery may be done to remove the testicles and reshape the genitals. The female hormone estrogen is then given during puberty.
When to Contact a Medical Professional
Call your provider if you, your son, or a male family member has infertility or incomplete development of male genitals. Genetic testing and counseling are recommended if PAIS is suspected.
Achermann JC, Hughes IA. Pediatric disorders of sex development. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 23.
Lin-Su, K, New MI. Ambiguous genitalia in the newborn. In: Gleason CA, Devaskar SU, eds. Avery's Diseases of the Newborn. 9th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 92.