What is Mixed Gonadal Dysgenesis?
Mixed gonadal dysgenesis (MGD) is a condition that changes how the body’s reproductive parts grow. It starts before a baby is born and can also affect changes that happen during puberty.
What makes a person’s body develop as a boy or a girl?
What makes a person’s reproductive parts grow?
Genes and hormones help the body’s reproductive parts grow and develop. Genes are like instruction codes, and hormones are chemical messengers that tell the body what to do. Most babies are born with 46 chromosomes, which carry those instructions. Two of the chromosomes help decide how the reproductive parts will grow. They are called the “sex chromosomes.” Most females have two X chromosomes (46,XX). Most males have one X and one Y chromosome (46,XY). Before a baby is born, these chromosomes help guide how the gonads develop.
Gonads are parts of the body that make hormones like estrogen and testosterone. These hormones help the body grow and change. Usually, gonads become ovaries in females and testicles in males. Ovaries mostly make estrogen and some testosterone. Testicles mostly make testosterone.
Before a baby is born, the amount of testosterone helps decide how the genitals (private parts) will look. If there is a lot of testosterone, the genitals usually look like a male’s. If there is not as much testosterone, they usually look like a female’s. When kids grow up and reach puberty, these hormones make the body change again.
What causes mixed gonadal dysgenesis?
For people with MGD, the chromosomes instructions are not the same in every cell inside their bodies. Some cells have one set of instructions, and other cells have a different set. This is called “mosaicism,” like a patchwork quilt or mosaic made of different pieces. When the mix happens with the sex chromosomes, this is called “sex chromosome mosaicism.” In people with MGD, some of their cells have chromosomes that are 46,XY. Other cells have 45,X, which means one of the sex chromosomes is missing. This mix of different chromosome patterns can happen in the same person, and sometimes there are even more combinations.
Because of this, their gonads grow in a different way than usual. Sometimes, the gonads didn’t grow all the way. These are called “dysgenetic” or “streak” gonads. They might not make any hormones before a baby is born. Other times, one or both of the gonads may have tissue from a testis or ovary. These gonads might make some hormones. Depending on which hormones are made and how much, a person with MGD might be born with body parts that look more like a female’s, a male’s or a mix of both.
How do the reproductive parts develop in people with Mixed Gonadal Dysgenesis?
In people with MGD, the body’s reproductive parts can grow in different ways. For example:
- Genitals (private parts): The penis may be small. The clitoris may be large. The genitals may have features of both a male and a female.
- Gonads: There may be a typical gonad on one side and an underdeveloped (“streak”) gonad on the other side.
- Vagina: Some people with MGD may have a small vagina. Some may have a urogenital sinus. A urogenital sinus is when the vagina and the tube carrying urine join up inside the body. Instead of having two holes on the outside of the body, there is just one.
- Womb or Uterus: People with MGD may or may not have a uterus.
- Puberty: Changes that happen during puberty depend on what hormones are made and how much. If testosterone is made during puberty, the genitals grow, the voice deepens, and facial hair grows.
How is Mixed Gonadal Dysgenesis Diagnosed?
MGD is often found when a baby is born and checked by a doctor. During the exam, the doctor might feel a testicle in the groin area instead of the scrotum. This is called an undescended testicle. If a gonad did not grow much, (“streak” gonad), the doctor will not be able to feel it. The baby’s genitals might not look like what is typical for a boy or a girl.
Sometimes MGD is found before birth through prenatal testing or later in life.
Testing may include:
- Karyotype – This is a blood test that looks at a person’s chromosomes, including the X and Y chromosomes. This may show if there is a mixed pattern of chromosomes.
- Hormone levels – This is a blood test to check which hormones the gonads are making and how much.
- Pelvic ultrasound – This is an imaging test that looks for gonads inside the body and for a uterus.
- Laparoscopy – This is a surgery using a small camera. The surgeon looks for the reproductive parts inside the body. The surgeon may also take small pieces of tissue (called a biopsy) for testing.
How is Mixed Gonadal Dysgenesis Treated?
Medical care
Children with MGD need regular checks to make sure they are growing and staying healthy. Doctors may do tests to look at their hormone levels and check their vision, hearing, kidneys and heart.
When children with MGD go through puberty, they may need hormone treatments to help their bodies change. Estrogen can help with breast growth, growing taller, and strong bones. Testosterone can help the penis grow, make the voice deeper and cause facial hair to grow.
Surgical Care
Most children with MGD do not need surgery right after they are born. However, if a gonad did not grow (“streak gonad”), it may need to be taken out later to help prevent cancer. If a testicle did not move down into the scrotum, doctors might need to do surgery to bring it down. Families can talk with the medical team about any other surgeries that might be needed.
Psychosocial Care
MGD is something a person lives with their whole life. Having a lifelong condition can sometimes make someone feel worried or unsure, and it can be stressful for their family too. Psychologists and social workers can help patients and families identify and address concerns. They can help people talk about their feelings and figure out what kind of support they need. They also help families think about how to share information about MGD with others. The goal is to support everyone and help them feel confident and cared for.
