Here is a description of some of the more common intersex traits, often referred to as differences of sex development (DSD) by the medical community. [read interACT’s Statement on Intersex Terminology]

Intersex is a term for biologically/ physically not being strictly male or female sex. Having one of over 30 differences of sex development is the reason this can occur.

To clarify, intersex or differences of sex development refer to the biology and/ or appearance (phenotype) of an individual, where as gender (how a person identifies) and sexual orientation (who a person is attracted to) are different things.

With these differences, variations in the usual path of prenatal development of parts of the reproductive system cause traits that we don’t usually expect in typical boys and girls. There may be unexpected patterns of the X and Y chromosomes (karyotype), gonads (which make sperm and eggs- the testes and ovaries), internal reproductive and urinary organs (uterus, fallopian tubes, bladder and urethra), or different looking genitalia.

Potential causes include genetic mutations, changes in number of sex chromosomes, atypical gonads, exposure to unusual levels of sex hormones, or atypical response to hormones. Intersex traits or DSD are not life-threatening, although they may be associated with a serious medical condition such as salt-wasting congenital adrenal hyperplasia (SW CAH).

46, XX salt-wasting CAH (SWCAH) is due to genetic mutations in enzymes of the adrenal gland, which sit on top of the kidneys. These enzymes are chemicals needed by the adrenal gland to make cholesterol into three important hormones that help to regulate the body’s functions: cortisol, aldosterone and androgen. If one of the enzymes needed to make cortisol and/or aldosterone is not working properly, the adrenal glands fail to work in a balanced way. They make too little cortisol and/or aldosterone, and more androgen than usual. When there is not enough cortisol or aldosterone, babies with SW CAH may become very sick. They can become dehydrated and lose blood pressure if not treated urgently. A baby with XX SW CAH has a uterus and ovaries, but the genital appearance may be female-typical, male-typical or in between. Babies with other types of CAH may not have genital difference.
AIS: Androgen Insensitivity Syndrome (AIS) occurs when babies are born with testes and one X and one Y chromosome (the typical pattern in boys), but their bodies are immune or unable to respond to androgens (hormones like testosterone). Since a penis and scrotum develop under the influence of androgen during prenatal development, a baby with AIS may develop genitalia that do not appear typically female. Babies with complete AIS have no response to androgens and look typically female, while babies with partial AIS (PAIS) may have genital difference (sometimes referred to as “ambiguity”), with external genitalia that appear mainly female, or mainly male, or anything on the spectrum between. Because androgen also influences sperm formation, some men do not discover that they have minimal PAIS until they see a doctor for infertility. During development, the testes also make a hormone (Mullerian inhibiting substance- MIS) that prevents formation of the uterus, fallopian tubes, and a small part of the upper vagina. Children with less sensitivity, or ability to respond to androgen, will appear closer to typical female. Their bodies are able to respond to estrogen. Because testes do make some estrogen, and the body can turn androgen into estrogen, these children may have some female development from their own hormones at puberty, and often supplement that with synthetic hormones to develop fully. Surgical removal of the testes (gonadectomy) may be recommended in PAIS because there may be a risk of cancer developing in the testes. The risk of cancer development before puberty in CAIS is very low, and it is accepted medical practice to leave CAIS testes in place for a more natural puberty.
46, XY complete gonadal dysgenesis (Swyer syndrome) occurs when a baby is born with one X and one Y chromosome, but the testes do not develop. During prenatal development, these babies develop typical female external genitalia and a small uterus. The underdeveloped gonads become fibrous tissue called “streaks”, neither testis nor ovary. These children need to take hormones for puberty. Because there is an increased risk of cancer developing in streak gonads, removal is commonly recommended
46, XY partial gonadal dysgenesis in a baby with XY chromosomes causes development of testes that do not function at the same level as typical testes. Sometimes the testes disappear or regress. Babies’ genitals can vary in appearance depending on how much the testes function. Tumors occur about 20-30 % of the time.
In 5 alpha reductase-3 deficiency (5 ARD deficiency) and 17beta-hydroxysteroid dehydrogenase-3 deficiency (17 BHSD deficiency), genetic mutations in XY babies with testes result in unusual levels of sex hormones. All hormones are made from cholesterol by enzymes, and these mutations change the function of enzymes needed to make androgens. Children with 5 ARD deficiency and 17 BHSD deficiency have XY chromosomes and testes, but their testes make a version of androgen that is weaker than usual. The appearance of babies’ genitalia may range from female-typical or vary along the spectrum of genital difference.At puberty, when levels of androgen increase dramatically, the large amount of weaker androgens can cause male-typical changes, like deepening of the voice, growth of facial hair, and muscle development. If a child does not want these changes, puberty can be blocked by medication. There are reports of fertility in adults with 5 ARD, but not 17 BHSD deficiency.
In typical sex development, the fetus develops two tiny organs called “proto-gonads”. In typical boys, the proto-gonads become testes, and they become ovaries in typical girls. Sometimes an ovotestis develops, which contains some ovary-type cells and some testis-type cells. Although a person may be born with two ovotestes, it is much more common for a person to be born with a typical ovary or testis on one side and an ovotestis on the other. Some people with ovotestes look fairly female-typical at birth, some look fairly male-typical, and some look more in-between. Because there may be many different chromosomal and internal anatomical combinations, children need other tests to evaluate their unique situations. The testicular part of ovotestes may have an increased cancer risk.
Girls with typical 46, XX chromosomes and ovaries may have atypical development of internal structures such as the vagina, the uterus, and the Fallopian tubes. MRKH Syndrome sometimes also involves differences in development of the skeleton, internal ears, and in rarer cases, the heart, fingers and toes.

Hypospadias, where the urinary opening (urethra) is located below the usual position on the tip of the penis, is one of the most common and visible genital variations. The urethra can also empty through the front wall of the vagina. Hypospadias is the most common birth difference in XY boys, seen in 1 out of every 125 to 300 live births. The cause of hypospadias is not known. The location of the opening of the urethra can vary from just below the tip of the penis down to just in front of the rectum. Bending of the penis, or chordee, is often seen with hypospadias, although they can occur separately.

Epispadias is similar to hypospadias because the urinary opening is not in its usual position. In epispadias, the urinary opening is located on the upper surface of the penis or in the middle of the clitoris. It is much less common than hypospadias. Epispadias usually happens in conditions called exstrophy, where the bladder, abdominal wall, and pelvis are not closed in the front as usual, but epispadias can also occur by itself.

More information can be found on the website of the Hypospadias and Epispadias Association, Inc.

Turner Syndrome (TS) is a variation of the chromosomes. Most typical women have two X chromosomes (XX). When a woman has one complete X chromosome, and the partner X chromosome that would typically be there is absent or smaller than usual, she has TS. This happens in about 1 in 2000 live births. It is sometimes found prenatally with amniocentesis.  In TS, the level of hormones needed to start puberty is unusually low because of a difference in development of the ovaries, which are called “streak gonads.” TS can also be discovered in adolescence when a girl does not go through puberty as expected.  Many girls and women with TS are petite, often under 5 feet tall. Other organs in the body, such as the heart, may also develop atypically.

Some people only have one X chromosome in some of their cells.  This is called “mosaic Turner Syndrome.” The other cells can have XX or XY chromosomes. Physical difference and gender identity in mosaic TS has will depend on what proportion of the cells and tissues have typical XX or XY chromosomes.

More information can be found at the website of the Turner Syndrome Society.

Klinefelter syndrome (Also called: XXY syndrome) is a genetic condition in which a male is born with an extra copy of the X chromosome. Klinefelter syndrome isn’t inherited, but rather occurs only as a result of a random genetic error after conception. Males born with Klinefelter syndrome may have low testosterone and reduced muscle mass, facial hair, and body hair. Most males with this condition produce little or no sperm. Treatment may include testosterone replacement and fertility treatment.

Thanks to AIS-DSD for providing the above information.