Overview
Atypical genitalia, formerly called ambiguous genitalia, is a rare condition in which an infant's genitals don't appear to be clearly male or female on the outside. In a baby with atypical genitalia, the genitals may not be developed fully or may look different from what is expected. Or the baby may have features of more than one sex. The sex organs on the outside of the body may not match the sex organs on the inside. And they may not match the genetic sex, which is determined by sex chromosomes: typically, XX for females and XY for males.
External genitals are the sex organs on the outside of the body. They include the opening of the vagina and the labia, clitoris, penis and scrotum. Internal genitals are the sex organs inside the body. They include the vagina, fallopian tubes, uterus, prostate, ovaries and testicles. Sex hormones are made by the ovaries and testicles, which also are called gonads. Genetic sex is set based on sex chromosomes. Typically, these sex chromosomes are a genetic female with two X chromosomes and a genetic male with one X and one Y chromosome.
Atypical genitalia is not a disease; it's a difference of sex development. Usually, atypical genitalia can be seen at or shortly after birth. The condition can be very distressing for families. Your medical team looks for the cause of atypical genitalia and provides information and counseling that can help guide decisions about your baby's sex and any needed treatment.
Symptoms
Your medical team will likely be the first to notice atypical genitalia soon after your baby is born. Sometimes, atypical genitalia may be suspected before birth. Atypical genitalia can vary in appearance. Differences may depend on when during genital development the hormone changes that affected development occurred and the cause.
Babies who are genetically female, which means they have two X chromosomes, may have:
- An enlarged clitoris, which may look like a penis.
- Closed labia, or labia that include folds and look like a scrotum.
- Lumps that feel like testicles in the fused labia.
Babies who are genetically male, which means they have one X and one Y chromosome, may have:
- A condition in which the narrow tube that carries urine and semen, called the urethra, doesn't fully extend to the tip of the penis. If the tube opening is on the underside of the penis, the condition is called hypospadias.
- A very small penis with the urethral opening closer to the scrotum.
- One or both testicles missing in what appears to be the scrotum.
- Testicles that remain in the body, also called undescended testicles, and an empty scrotum that has the appearance of labia with or without a micropenis.
Causes
Atypical genitalia usually happen when hormone changes during pregnancy stop or disturb an unborn baby's developing sex organs. An unborn baby also is called a fetus.
How sex organs form in the womb
A baby's genetic sex is set at conception, based on the sex chromosomes. Conception is when the egg from one parent meets the sperm from the other parent. The egg contains an X chromosome. The sperm contains either an X or a Y chromosome. A baby who gets the X chromosome from the sperm is a genetic female with two X chromosomes. A baby who gets the Y chromosome from the sperm is a genetic male with one X and one Y chromosome.
Male and female sex organs develop from the same tissue. Whether this tissue becomes male organs or female organs depends on the chromosomes and the presence or absence of hormones called androgens. Androgens cause the development of male genitals.
- In a fetus with a Y chromosome, a region on that chromosome triggers the development of testicles, which make androgens. Male genitals develop in response to these hormones from the fetal testicles.
- In a fetus without a Y chromosome, and without the effects of androgens, the genitals develop as female.
Sometimes a chromosomal change may make it hard to figure out the genetic sex.
How atypical genitalia occurs
A change in the steps that influence fetal sex development can result in a mismatch between the appearance of a baby's external genitals and the baby's internal sex organs or genetic sex, typically XX or XY.
- If a genetic male fetus doesn't make hormones called androgens or doesn't have enough of these hormones, it can cause atypical genitalia. Exposure to androgens during development in a genetic female fetus results in atypical external genitalia.
- Changes in certain genes can affect fetal sex development and cause atypical genitalia.
- Atypical genitalia also can be a feature of certain rare or complex syndromes that affect many organs. These syndromes can include chromosome changes such as a missing sex chromosome or an extra one.
Sometimes it's not possible to find the cause of atypical genitalia.
Possible causes in genetic females
Causes of atypical genitalia in genetic females may include:
- Congenital adrenal hyperplasia. Certain forms of this genetic condition cause the adrenal glands to make too much of hormones called androgens.
- Exposure to certain hormones before birth. Some drugs that contain androgens or that cause a pregnant person's body to make these hormones can cause developing female genitals to become more masculine. A developing fetus also may be exposed to too much of the hormones that cause the development of male genitals if the pregnant person has a condition that causes hormones to be out of balance.
- Tumors. Rarely, a tumor in the pregnant person can make hormones that cause the development of male genitals.
Possible causes in genetic males
Causes of atypical genitalia in genetic males may include:
- Problems with testicle development. This may be due to changes in genes or due to unknown causes.
- Androgen insensitivity syndrome. In this condition, developing genital tissues don't respond as they should to hormones made by the testicles.
- Problems with the testicles or testosterone. A variety of problems can interfere with the testicles' activity. These can include problems with how the testicles are formed and problems with making the hormone testosterone. This also may include problems with certain proteins in cells that tell the cells to respond to testosterone.
- 5-alpha-reductase deficiency. Not having enough of this enzyme causes problems with making hormones that cause the development of male genitals.
Risk factors
Family history may play a role in the development of atypical genitalia. This is because many differences of sex development result from gene changes that can be passed down in families. Possible risk factors for atypical genitalia include a family history of:
- Unexplained deaths in early infancy.
- Infertility, not having menstrual periods or having a lot of facial hair in females.
- Atypical genitalia.
- Atypical physical development during puberty.
- Congenital adrenal hyperplasia, a group of genetic conditions that affect the adrenal glands and are passed down in families.
If your family has a history of these risk factors, talk with your healthcare professional before trying to get pregnant. Genetic counseling also can help in planning ahead.
Complications
Complications of atypical genitalia may include:
- Infertility. Whether people with atypical genitalia can have children depends on the specific diagnosis. For example, genetic females with congenital adrenal hyperplasia usually can get pregnant if they so choose.
- Higher risk of certain cancers. Some differences of sex development are linked with a higher risk of certain types of cancer.