| Name | Short Description | Estimated number |
| Complete Androgen Insensitivity Syndrome (CAIS) | The body of a baby in the womb is completely insensitive to the androgen hormone (incl testosterone and DHT) that are produced because the 'androgen receptor' doesn't recognise the androgen hormones, or: does not know what to do with the androgens. Girls will usually only be diagnosed towards end of puberty when they don't have periods. |
1/40 000 women |
| Partial Androgen Insensitivity syndrome (PAIS) | The body of a baby in the womb is partially insensitive to the androgens (incl testosterone and DHT) that are produced. This happens when the 'androgen receptor' only partially recognises the androgen hormones, or: only knows a little bit of what to do with the androgens. Children can be diagnosed at birth or girls can be diagnosed in teenage years when they don't have periods or when their bodies respond partially to the androgens. | Rare |
| Persistent Müllerian Duct Syndrome (PMDS) | Babies are born with a typical penis, and they also have a uterus and fallopian tubes. The uterus and fallopian tubes are derived from a structure called the 'Müllerian duct' during development of the foetus. Testes are usually undescended as they are attached to these structures. | Rare |
| Testicular Regression Syndrome (vanishing testes syndrome) | Boys are born with a complete or partial absence of one or both testes but development of a typical penis or sometimes hypospadias. This occurs when the testis regresses or is damaged in the later stages of pregnancy after the external structures have started to form. For more information you can contact the Anorchidism Support Group (UK). |
