Disorders of Sexual Differentiation | Symptoms and Causes

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What are the symptoms of disorders of sex differentiation?

Symptoms of a disorders of sex differentiation (DSD) depend on what type of condition your child has. In most cases, children with DSDs have genitalia that are atypical in appearance. This may include ambiguous genitalia or dysgenetic (malformed) gonads.

DSD can also be limited to a child’s internal structures.

Ambiguous genitalia

Ambiguous genitalia refers to sexual organs that aren't well formed or aren't clearly male or female. At conception, a fetus's gender is already determined based on the 23rd pair chromosome it inherited from the parents. Females have two X chromosomes and males have an X and a Y chromosome. Even though the gender is set, the fetal tissue that will eventually become the female ovaries or male testes (gonads) has not yet begun to take its form. If the hormonal process that causes that tissue to become male or female is disrupted over the following weeks, ambiguous genitalia can develop.

The biology behind ambiguous genitalia can be hard to understand. Breaking it down in the following steps can make it easier:

  • The sexual organs of males and females develop from the same fetal tissue. The same tissue that becomes a penis in a male becomes a clitoris in a female.
  • The main factor controlling the next step is male hormones. The presence of male sex hormones causes male organs to develop and the absence of male hormones causes female organs to develop.
  • Without enough male hormones, a genetic male will develop ambiguous genitalia. Likewise, a genetic female will develop ambiguous genitalia if male hormone is present.

Your obstetric team will most likely be the first ones who notice the ambiguous genitalia. 

Characteristics of ambiguous genitalia in genetic females include:

  • an enlarged clitoris, or what appears to be a small penis
  • a concealed vagina

Characteristics of ambiguous genitalia in genetic males include:

  • an abnormally small penis with the urethral opening nearer to the scrotum
  • no recognizable male genitalia in the most severe cases
  • the absence of both testicles in what appears to be the scrotum

With proper medical management, most children with ambiguous genitalia will lead healthy and normal lives. Sex assignment and corrective surgery are necessary in allowing your child to lead a fairly normal life as a boy or a girl. As a child grows up and enters puberty, there is a slight chance that they will identify with a sex other than the one they were assigned. In this case, a gender transition may be necessary. It’s recommended that physicians wait until the child is around 16 years old before beginning the hormone therapy process involved in a transition.

What causes disorders of sex differentiation?

Sex development starts at the time of conception and continues through late adulthood. The normal pattern of sexual development looks like this:

Chromosomes and gonads

Gonads are the body’s primary sex organs. They form according to a specific chromosomal pattern:

  • The mother’s egg and the father's sperm start out with 23 chromosomes during conception. During this time, a child inherits 23 chromosomes from each parent, ending up with a total of 46 chromosomes.
  • Normally, the egg from the mother contributes one X chromosome and the sperm form the father contributes either one X chromosome or one Y chromosome.
  • A child is born female if she inherits two X chromosomes (XX). A child is born male if he inherits one X chromosome and one Y chromosome (XY).
  • As a result of this chromosomal pattern, boys develop gonads called testicles and females develop gonads called ovaries.

Hormones

  • The primary function of the gonads is producing hormones. Normally, testes produce the male hormone testosterone and ovaries produce the female hormone estrogen.
  • These hormones aid in the formation of sex organs. The testosterone produced from the male testes drive the formation of a penis. The estrogen produced by female ovaries result in the formation of a vagina.

Sexual development in children with disorders of sex differentiation

With so many stages of sex development, there are a lot of opportunities for a fetus to take a path that not typical for a boy or a girl. When an atypical path of development is taken, the resulting condition is known as a “disorder of sexual development.”

There are several ways this can happen:

  • Some disorders are genetic (chromosome variations).
  • Some are present at birth (congenital) but not genetic.
  • Some are variations in psychosocial development.
  • DSDs can also be idiopathic, meaning they have no identifiable cause.
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