Disorders of Sexual Differentiation

What are disorders of sexual differentiation?

Disorders of sexual differentiation (DSD) describe a wide range of conditions in which development of the sex organs does not occur as it normally would. These conditions involve mild to significant variations in reproductive organ development, sex development, and gender identity. The most common DSDs are congenital adrenal hyperplasia and mixed gonadal dysgenesis.

What are the types of disorders of sex differentiation?

The most common DSDs detected in newborns include:

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia is a genetic disorder of the adrenal glands. If your child has this condition, it means that their adrenal glands don’t produce enough of the vital hormones cortisol and aldosterone. As a result, the body produces too much androgen. Females born with this condition are typically born with an enlarged clitoris, but with normal internal reproductive structures. Males born with this condition have normal genitals at birth, but may develop a large penis, smaller testes and a deeper voice well before puberty. Treatment for females may involve hormone replacement therapy, reconstructive surgery, and psychological support. For males, medical treatment is indicated.

Mixed gonadal dysgensis

Mixed gonadal dysgenesis is a disorder of sexual differentiation in which a chromosomal abnormality causes a child to be born with two different gonads:  An undescended testicle and a dysgenetic (malformed) “streak” gonad. A child with mixed gonadal dysgenesis has an undescended testicle on one side and a dysgenetic (improperly developed) gonad on the opposite side. The two different gonads can’t produce normal sex hormones, resulting in malformed sex organs. Gender assignment is important for treatment purposes as well as the emotional well being of children as they grow older, and remains a crucial part of the treatment; however, the complexity varies depending on your child’s exact anatomy.

Although less common, other types of DSDs include:

Impaired testicular development 

Impaired testicular development occurs either because of an inherited genetic defect or for an idiopathic (unknown) reason. Typically, a child’s body is unable to produce testosterone, which prevents the testicular structures from developing. Impaired testicular development is not the same as having an undescended testicle. Treatment may involve surgery. The child’s clinician will advise and work with the family on other gender and related considerations.

Androgen insensitivity syndrome

Androgen insensitivity syndrome (AIS) is an inherited genetic disorder in which a child is born with chromosomes and gonads (with one X chromosome and one Y chromosome), but the cells in the body do not respond to the male sex hormone androgen. As a result, the child displays female characteristics despite being genetically male. AIS can be either complete (in which case the child appears completely female), or incomplete (in which case, the external appearance may be ambiguous). Treatments can include removal of the undescended testes (to eliminate the risk of cancer) and taking estrogen replacement medication.

How we care for disorders of sex differentiation

At Boston Children's Hospital, we understand that a diagnosis of a disorder of sexual differentiation (DSDs) can cause a lot of anxiety. You probably have a lot of questions and uncertainty about your child’s sexuality and health. Our team of clinicians in the Disorders of Sexual Development (DSD) and Gender Multispecialty Service (GeMS) provide some answers to those questions. When you meet with our team of experts, they’ll be able to explain your child’s condition and options in more detail.

Remember that seeking out information is not only necessary but also empowering — it allows you to partner with your child’s care providers to make the best decisions for your family.

Our areas of innovation for disorders of sex differentiation

Years ago, babies born with ambiguous genitalia were routinely "assigned" a gender by their physicians, and underwent treatment to match that assignment. Today, decision-making is much more individualized and is done in close consultation with the family.

Beyond evaluating, diagnosing, and treating infants, children, and adolescents with disorders of the genital and urinary organs, the Gender Multispecialty Service (GeMS) Clinic at Boston Children's Hospital is also looking to the future. Our physicians and researchers are leading a number of studies and trials that hold great promise in the detection and treatment of this condition.