Disorders of sex development (DSDs) are a group of rare conditions where the reproductive organs and genitals do not develop as expected.
If you have a DSD, you will have a mix of male and female sexual characteristics.
You may have the sex chromosomes (bundles of genes) normally associated with being female (XX chromosomes) or male (XY chromosomes), but your reproductive organs and genitals may be of the opposite sex, not clearly male nor female (ambiguous or atypical), or a mixture of both.
This occurs because of a difference with your genetic make-up and/or how you respond to the sex hormones in your body. These conditions can be inherited, but often they occur randomly for no apparent reason.
Types of DSDs
There are different types of DSD, and each has a different cause. Below are some examples.
Female with ambiguous or male-looking genitals
Some people have XX (female) chromosomes with normal ovaries and womb, but their genitals appear ambiguous or male. For example, they may have an enlarged clitoris resembling a penis and their lower vagina may be closed.
Doctors refer to this condition as 46,XX DSD.
The most common cause is a condition called congenital adrenal hyperplasia (CAH). If your child has CAH, they lack a particular enzyme (protein) that their body needs to make hormones called cortisol and aldosterone.
Without these, the body produces more androgens (male sex hormones). If the affected child is female, then the raised androgen levels before birth cause the genitals to become more male in appearance.
This condition can also lead to serious health issues, such as life-threatening kidney problems that need to be treated as soon as possible.
For support and more information on CAH, you can visit the CAH support group.
Female with normal external genitals but some internal male structures
Some women have XY (male) chromosomes but their external genitals may appear entirely female or atypical. The womb may be present or absent and the testicles may be absent or not properly formed.
Doctors refer to this condition as 46,XY DSD.
There are several different causes of this condition. One possible cause is androgen insensitivity syndrome (AIS), where the body ignores androgens or is insensitive to them, so development is female. The testes usually remain inside their body and the womb does not develop.
AIS is thought to occur in around one in every 20,000 births, although the exact figures are unknown.
For support and more information on AIS, you can visit the AIS Support Group.
A mix of male and female characteristics
People with this very rare type of DSD have both ovarian and testicular tissue (for example, one ovary and one testis), and their genitals may appear female, male or a mix of both.
Most people with this type of DSD have XX (female) chromosomes and, although the cause is not usually clear, some cases have been linked to genetic material normally found on the Y chromosome becoming misplaced on the X chromosome. Doctors refer to this condition as 46,XX ovotesticular DSD.
Normally formed genitals but abnormal sexual development
Some people have neither XY nor XX chromosomes – for example, they may only have one X chromosome (XO), or they may have an extra chromosome (XXY).
Physically, their sex organs are normally formed as either male (testes and a penis) or female (ovaries, womb and a vagina), but they may not go through normal sexual development at puberty. For example, a child with female sex organs may not start having periods and may have small breasts.
Doctors refer to this condition as sex chromosome DSD.
An example is Turner syndrome, where a female is missing an X chromosome. Girls or women with Turner syndrome are usuallyinfertile and their height is shorter than average.
Female with an absent womb
Some females are born with an underdeveloped or absent womb, cervix and upper vagina, but the ovaries and external genitalia (vulva) are still present and they still develop breasts and pubic hair as they get older.
This is known as Rokitansky syndrome (also called Mayer-Rokitansky-Küster-Hauser or MRKH syndrome). It’s thought to affect around one in every 4,000 to 5,000 females.
The cause of Rokitansky syndrome is not clear, but it’s not related to the chromosomes because girls and women with it have the normal XX chromosomes.
Often the first sign of Rokitansky syndrome is that a girl does not start having periods. Sex may also be difficult because the vagina is shorter than normal.
As they have no womb, women with Rokitansky syndrome cannot become pregnant, but it’s sometimes possible to take eggs from their ovaries, fertilise them, and implant them in another women (surrogate).
What happens after birth
Some cases of DSD are suspected soon after birth because of obvious signs such as undescended testicles or an atypical or ambiguous genital appearance.
In such cases, a number of tests may be carried out to help confirm the diagnosis and identify any medical problems that may require immediate treatment.
These tests may include a further physical examination of your baby carried out by a specialist, an ultrasound scan to examine their internal organs, and blood tests.
Your care team may advise you to delay registering your child's birth for a few days while these tests are carried out. Afterwards, the results will be explained to you and you will have a discussion with specialists about whether to bring your baby up as a boy or a girl.
Emergency treatment is rarely needed for a DSD, but the team of specialists can also talk to you about your options regarding immediate or delayed treatment with hormone therapy or surgery.
Advice for parents of older children
Sometimes a DSD may be diagnosed if an older child does not develop normally in puberty. For example, your child may not start the normal puberty changes or may start puberty but not start periods. You should speak to your GP if you have any concerns about your child’s development at puberty.
They should refer your child to a specialist, usually a consultant in paediatric endocrinology or an adolescent gynaecologist.
A team of different healthcare professionals will work together to understand your child's condition and offer you and your child support and advice.
As your child grows up, they may need hormone therapy and psychological support, and they may eventually decide they want surgery to change their physical appearance. With the right care and support, many people with DSDs come to terms with their condition and live happily.
If you think you have a DSD
If you think or know that you have a DSD, help and support is available.
You should speak to your GP initially, as they will be able to refer you to a team of specialist healthcare professionals who can offer support and advice.
Most people with a DSD stay with the gender they were assigned as a baby, but if you feel the gender you were assigned does not represent who you are, you may wish to change your gender. This will be something you can discuss with your team of specialists.
If you have a DSD, you may be infertile and you may need hormone therapy and psychological support, but the right care and support can help you come to terms with your condition and lead a normal life.
If you have a DSD, or you are the parent of a child who does, you may find it useful to contact or join a support group.
These groups can often offer more information and advice about living with a DSD, and they may be able to put you in contact with others who have been in a similar situation to you.
National DSD support groups include:
Androgen Insensitivity Syndrome Support Group
Congenital Adrenal Hyperplasia Support Group
Your care team may also be able to recommend support groups in your local area.
Disorders of sex development (DSDs) are also sometimes called intersex conditions.
Some doctors also used to refer to a person with a DSD as a hermaphrodite. However, this term is longer used as it is misleading and can be insensitive.
DSDs should not be confused with gender dysphoria, which is also known as transsexuality or being transgender. Gender dysphoria is where the reproductive organs and genitals have developed normally, but the person feels that their gender identity (their sense of what sex they are) does not match their biological sex.