DSD stands for differences of sex development (sometimes called disorders of sex development). It refers to a group of congenital conditions where a person’s chromosomes, hormones, or reproductive anatomy develop differently from what is typically expected for male or female bodies. Roughly 1 in 1,000 to 1 in 4,500 babies are born with some form of DSD.
What DSD Actually Means
During fetal development, several biological systems work together to shape a person’s sex characteristics: chromosomes send genetic signals, genes like SRY on the Y chromosome trigger the formation of testes or ovaries, and hormones produced by those organs then guide the development of internal and external anatomy. A DSD occurs when any step in that chain unfolds differently than usual. The result can range from subtle hormonal differences that aren’t noticed until puberty to visibly atypical genitalia at birth.
The term “DSD” was formally adopted in 2006 by an international group of medical specialists to replace older labels like “intersex conditions,” “hermaphroditism,” and “pseudohermaphroditism,” which were considered stigmatizing and imprecise. Some clinicians and patient advocates now prefer “differences” of sex development over “disorders” to reflect that these are natural biological variations rather than diseases. Both versions of the acronym appear in medical literature.
The Most Common Types
Congenital Adrenal Hyperplasia (CAH)
CAH is the single most common cause of DSD. It happens when the adrenal glands can’t produce enough of the hormone cortisol, usually because of a missing enzyme called 21-hydroxylase. Without that enzyme, the body diverts its hormone production toward androgens (male-type hormones) instead. In female newborns, the excess androgens can cause external genitalia that appear ambiguous, even though the internal organs, including the ovaries, uterus, and fallopian tubes, develop normally. Male newborns may have enlarged genitalia. In more severe forms, children also lose too much salt through their kidneys, which can become a medical emergency in the first weeks of life.
A milder version, called nonclassic CAH, sometimes goes undetected until childhood or even adulthood, when signs like early puberty, acne, or unusual growth patterns prompt testing.
Androgen Insensitivity Syndrome (AIS)
AIS results from a change in the gene that builds androgen receptors, the proteins that allow cells to respond to testosterone. In complete androgen insensitivity, a person has XY chromosomes and internal testes, but the body cannot use testosterone at all. The result is external anatomy that looks typically female, though there is no uterus and menstruation does not occur. The testes remain inside the abdomen or pelvis. Many people with complete AIS don’t learn about their condition until puberty, when periods never start.
Partial androgen insensitivity falls along a wide spectrum. Some individuals have genitalia that appear typically female, others have features of both, and some appear typically male. The degree depends on how much androgen receptor function remains.
Swyer Syndrome
In Swyer syndrome, a person has XY chromosomes but the gene that normally triggers testis formation (SRY) doesn’t function properly. Without working testes, the body defaults to developing female external anatomy and a uterus. The gonads, however, don’t develop into functional ovaries or testes. They remain as small streaks of tissue. Swyer syndrome is rare, affecting roughly 1 in 30,000 to 1 in 80,000 births. Because the external appearance is typically female with no genital ambiguity, it often goes unnoticed until puberty doesn’t progress on its own.
Sex Chromosome Variations
Some DSDs involve having extra or missing sex chromosomes. Turner syndrome (one X chromosome instead of two) affects girls and women, causing short stature and ovaries that don’t fully develop. Klinefelter syndrome (two X chromosomes plus a Y) affects boys and men, often causing taller stature, reduced testosterone, and smaller testes. These chromosomal variations are sometimes grouped under the DSD umbrella because they affect how sex characteristics develop, though many people with these conditions don’t think of themselves as having a DSD.
How DSD Is Diagnosed
Some DSDs are identified immediately at birth when a baby’s genitalia don’t fit neatly into typical male or female categories. Others aren’t discovered until puberty doesn’t arrive on schedule, or until a couple investigates infertility in adulthood. The diagnostic process typically starts with a chromosome test called karyotyping, which reveals whether someone has XX, XY, or a different chromosomal pattern. That result helps doctors classify the type of DSD and decide what further testing is needed.
From there, blood tests measure hormone levels, including testosterone, cortisol, and related hormones, to identify whether the body is producing or responding to them normally. Imaging such as ultrasound or MRI can show whether a uterus, ovaries, or testes are present internally. In some cases, more advanced genetic testing looks for specific gene changes, examining genes like SRY, AR, and others known to play roles in sex development. Occasionally, a biopsy of gonadal tissue is needed when other tests don’t give a clear answer.
How DSD Is Managed
Because DSDs affect so many different body systems, care is coordinated by a multidisciplinary team. A typical team includes pediatric endocrinologists (who manage hormone-related issues), geneticists and genetic counselors, urologists or gynecologists, psychologists or psychiatrists, and social workers who help families navigate practical and emotional challenges. Getting connected to this kind of team early, ideally in infancy, means the right specialists are already in place whenever a need arises.
Treatment depends entirely on the specific condition. Some children with CAH need daily hormone replacement to keep cortisol and salt levels stable. Others may benefit from hormone therapy at puberty to promote the development of secondary sex characteristics like breast growth or voice deepening. Surgical decisions, particularly those involving genital anatomy, have become increasingly cautious over the past two decades. Many medical guidelines now emphasize waiting until a child is old enough to participate in decision-making, rather than performing irreversible procedures in infancy.
Psychological Support and Disclosure
One of the biggest shifts in DSD care has been around openness. The American Medical Association considers it unethical to withhold medical information from patients, and current consensus guidelines encourage honest, age-appropriate communication among doctors, parents, and children. That doesn’t mean telling a toddler their full genetic profile. It means building understanding gradually, matching the level of detail to the child’s developmental stage.
Both chronological age and emotional maturity factor into when and how much to share. Parents sometimes worry that disclosure will cause distress, but research consistently supports the idea that secrecy tends to cause more psychological harm than honesty does. Teams typically include psychologists who help parents navigate these conversations and who provide direct support to children and teens as they process their diagnosis. Peer support groups also play a significant role, connecting families and individuals with others who share similar experiences.
Hormones and Long-Term Health
Hormone levels in people with DSD don’t always fall within typical male or female reference ranges. For context, testosterone in adult men typically stays above 8.4 nmol/L, while in adult women it’s usually below 2.7 nmol/L. Some women with conditions like AIS or other DSDs have testosterone levels well above that female range, sometimes exceeding 8 nmol/L. This overlap matters for health monitoring because testosterone and estrogen influence bone density, cardiovascular health, and muscle mass throughout life.
People with certain DSDs may need ongoing hormone monitoring and, in some cases, lifelong hormone replacement therapy. Those born without functional gonads, as in Swyer syndrome, need supplemental hormones to go through puberty and to protect bone health in adulthood. Fertility varies widely depending on the specific condition. Some people with DSD can conceive naturally, others may need assisted reproduction, and some are infertile. A reproductive endocrinologist can help clarify individual options.