Variation of Sex Development (VSD)

How Reproductive Organs Develop

Every person has 23 pairs of chromosomes in each cell of their body. Sex is determined by the 23rd pair: Females have two X chromosomes, and males have one X and one Y chromosome.

Sex is determined at conception and the baby’s reproductive organs begin to form around six weeks. If a Y chromosome is present, the baby will begin to develop testes, followed by the penis, scrotum and urethra. If there is no Y chromosome, a female baby will form ovaries, uterus, fallopian tubes and urethra. Sex organ formation is facilitated by certain hormones secreted during fetal development.

What Is Variation of Sex Development (VSD)?

Many genetic, hormonal, and environmental factors can affect the developing baby and lead to atypical genitalia. Children with VSDs may appear to have characteristics of both sexes, which may make it harder to identify sex at birth. Examples include:

• Baby has male (XY) chromosomes but has genitals that appear female.
• Baby has female (XX) chromosomes but has genitals that appear male.
• Baby has both ovarian and testicular tissues. Genitals may appear male, female or both.
• Sex organs are typical but with an variation in chromosome arrangement.

Causes of VSDs include:

• Genetic mutations. These can be passed down from a parent or can be spontaneous changes without a known cause.
• Hormone insufficiency can affect reproductive organ development.
• Exposure to hormones or medications during pregnancy.

Types of Variation of Sex Development

Variation of sex development include:

• 5-alpha-reductase deficiency: Children with this inherited condition lack an enzyme needed to help the male sex organs develop. As a result, the child will have normal male chromosomes but ambiguous genitalia. The disorder is inherited through an autosomal recessive gene, which means both parents must carry the gene and pass it on to their son.
• Androgen insensitivity syndrome: A child with this inherited syndrome is unable to respond to male sex hormones. As a result the child will have normal male chromosomes but female external genitalia. The disorder is caused by a problem on the X chromosome, so can be passed from mother to son; if the gene is passed to a daughter, she can become a carrier for the disorder.
• Congenital adrenal hyperplasia (CAH): This condition affects girl babies. It is caused by a lack of an enzyme in the adrenal gland that is necessary for sex organ development and other body functions. Girls with CAH may be born with external male genitalia. The disorder is inherited through an autosomal recessive gene, which means both parents must carry the gene and pass it on to their child.
• Gonadal dysgenesis: Child has an undeveloped sex organ. Internal organs are often female but external genitals vary between normal female and normal male.
• Pure gonadal dysgenesis: This condition affects girls. The child has male chromosomes, and female internal and external reproductive organs that are underdeveloped.
• True hermaphroditism: Baby has internal sex organs for both sexes and external genitalia that is partly ambiguous. Chromosomes may be either normal female, normal male or a mixture.

Diagnosing Variation of Sex Development

While VSDs are sometimes diagnosed at birth, other times they may not be diagnosed until puberty or even adulthood.

In addition to a physical exam, your child’s healthcare provider may perform tests such as:

• Chromosome/genetic testing: To identify abnormal chromosome or genetic mutations.
• A pelvic ultrasound or magnetic resonance imaging (MRI): Imaging test to check for female sex organs.
• Genitourethrogram: Uses X-ray imaging to view the urethra and/or vagina.
• Cystoscopy/vaginoscopy: A small light and camera is attached to a thin flexible tube and inserted into the urethra or vagina to examine internal urinary tract and reproductive organs.
• Hormonal testing: To check for abnormal levels of sex hormones.

Managing VSDs in Children

Treatment for VSDs will depend on the specific disorder as well as the severity. Treatments may include medication such as hormone therapy or reconstructive surgery to change the appearance of the genitals. Unless it is medically necessary, surgery could be delayed until the child is old enough to make their own decisions.

Children with VSDs may also be at a higher risk for other conditions, including autoimmune diseases, congenital heart disease, high/low blood pressure, infertility, osteoporosis and metabolic diseases. Your child may require care from other specialists as necessary to diagnose and manage related conditions. This may include pediatric urologists, endocrinologists, gynecologists, geneticists and psychologists.

While children with VSDs may require specialized care, with proper management, they can live full, active and happy lives just like their peers.