Mixed Gonadal Dysgenesis

At Boston Children’s Hospital, we understand that a diagnosis of mixed gonadal dysgensis (MGD) comes with a lot of questions and uncertainty about your child’s sexuality and health. We’ve provided some answers to those questions here, and when you meet with our team of experts, they’ll be able to explain your child’s condition and options in more detail.

 What is MGD?

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 child and your family.

  • MGD is a disorder of sexual differentiation in which a chromosomal abnormality causes a child to be born with two different gonads:  an undescended testis and a dysgenetic (malformed) “streak” gonad.
  • MGD is one of the most common disorders of sexual dysfunction and the second most common cause of ambiguous genitalia (sexual organs that aren't well formed or aren't clearly male or female).
  • Most cases of MGD involve an abnormal chromosomal pattern called a mosaic. This means that the child is born with the chromosomes: 46XY, 45XO
  •  This chromosomal abnormality drives the formation of two different gonads: an undescended testicle on one side, and a dysgenetic (improperly developed) gonad on the opposite side.
  • Children with MGD typically have “ambiguous” genitalia, making it difficult to classify them as “boys” or “girls”.
  • The two different gonads can’t produce normal sex hormones, resulting in malformed sex organs.

Are there any other medical conditions associated with MGD I should be concerned about?

MGD is usually an isolated issue that doesn’t involve a child’s other organ systems. In very rare cases, children with MGD have an increased risk for certain medical conditions, such as:

  • Denys-Drash syndrome (DDS), which affects a child’s kidneys in addition to malformed sex organs. Children with DDS are predisposed to kidney failure.
  • Wilm’s tumors, a cancerous tumor in the cells of the kidney.

What causes mixed gonadal dysgenesis (MGD)?

In a normal pattern of sexual development, chromosomes, gonads, and hormones function like this:

Chromosomes and Gonads

  • Gonads are the body’s primary sex organs. They form according to a specific chromosomal pattern.
  • Normally, females are born with two X chromosomes (XX) and males are born with 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.


  • 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 phallus. The estrogen produced by female ovaries result in the formation of a vagina.

Sexual development in children with MGD

  • Children with MGD are born with an abnormal chromosomal pattern called a mosaic: 46 XY, 45 XO
    • Typically, the child has the normal male chromosome XY. The XY chromosome causes a testis to form. In some cases, this testis is undescended.
    • Because XO isn’t a normal chromosomal pattern, it results in the formation of a dysgenetic or malformed gonad. This is referred to as a “streak gonad”
    • The reason why children with MGD aren’t born as “boys” or “girls” is due to the ambiguity of the external genitalia.
  • As a result of having two abnormal gonads, a child with MGD can’t produce normal amounts of sex hormones.

MGD in the child might look like this:

  • The side with the undescended testis is able to produce testosterone. As a result, a fairly normally scrotum develops.
  • On the side of the streak (improperly developed) gonad, testosterone is not being produced. Instead, female reproductive organs such as a hemi-uterus and fallopian tube are present.

What are the symptoms of MGD?

  • People with MGD are asymptomatic, which means that they present no observable signs of the disorder. MGD can only be detected through medical examination and diagnostic tests.
  • Children with MGD also tend to be shorter than average


Q: After sex assignment, can a child with MGD lead a fairly normal life as a boy or girl?

A: Yes. Using surgery to correct malformed genitalia will allow your child to lead a fairly normal life as a boy or a girl. However, he or she may look and feel slightly different from the average child.

Q: Can my child have children?

A: No matter which gender they’re raised in, children with MGD are infertile. Those reared as female are infertile because they don’t have an ovary. Males with MGD are infertile because they have an undescended testis, which is dysgenetic (abnormal). While it’s possible that some people with MGD might be able to have children with intensive assisted reproductive techniques, it is unknown.

Q: Will a child be able to function sexually?

A: Yes. With the proper surgical correction, children ought to be able to function sexually in a reasonably normal way.

Q: Are there any complications as children with MGD reach their teen years and go through puberty?

A: As children with MGD grow older, doctors want to make sure that their hormone production is adequate enough to enter puberty.  A child reared as female will have to take medications containing the female hormone estrogen in order to enter puberty and develop normally. Later on in life, a reassessment of her functioning will be done. This evaluation will be done under anesthesia. As for a male child, the doctors will follow his blood testosterone level to make sure that it remains adequate.

Q: How can I help my child cope with his condition?

A:  Support from family and health care providers go a long way in helping your child build healthy self-esteem. Making sure that your child receives psychological counseling is also an important part in maintaining his emotional and mental health. Children’s offers a variety of support services to parents and children.

If you are having trouble coping with your child’s MGD, we offer many support services that can help you to develop parenting strategies and feel less anxious.

Q: Will my child need hormone replacement medication? Why?

A: It depends on the gender of the child.  A male child with a testis that’s functioning well enough to produce male hormones won’t need hormonal therapy. Children reared as females would need hormonal therapy because they don’t have a normal ovary.

Q: Should my child get corrective genital surgery?

A: After your child is diagnosed with MGD, you should have a discussion with your family and your child’s doctor about sex assignment. Deciding on a sex assignment depends on the anatomic findings, so it will vary from child to child.

Corrective surgery is needed most cases because the two gonads do not match up. If you raise the child a male, the female ductal structures on the opposite side would need to be removed. If you raise the child as a female, because the phallus is small and the likelihood is that she would function better as a female, then the testis would need to be removed.

Questions to ask your doctor

You will probably have a lot of questions on your mind before meeting with your child’s doctor. At the appointment, it can be easy to be overwhelmed with information and forget the questions you wanted to ask.

A lot of parents find it helpful to jot down questions beforehand. That way, when you talk to your child’s clinician, you can be sure that all your concerns are addressed. Remember that physicians are open to learning from families too. Attend conferences, read up on updated materials and don’t be afraid to share what you have learned.

Some questions you might ask include:

  • How do I make a decision about sex assignment?
  • What are the side effects of hormone replacement medication?
  • Which health care providers should my child see and how often?
  • How do I explain MGD to family and friends?
  • When should I tell my child about her MGD? How can I explain in a way he will understand?
  • Should my child get corrective genital surgery?