What is mixed gonadal dysgenesis?

Also known as: MGD, disorder of sex development, DSD.

Sex is determined by the presence in cells of sex chromosomes X and Y. Girls are born with two X (XX) chromosomes while boys have an X and a Y (XY) chromosome. The gonads (ovaries or testicles) develop under the guidance of the sex chromosome patterns. During fetal growth the ovaries produce estrogen which assists the growth of the vagina and uterus. Testicles produce testosterone as well as a substance to stop the formation of female sex organs, that is needed to form male sex organs. 

Mixed gonadal dysgenesis is a sex developmental disorder where the gonads are abnormal from there being some cells with XY chromosomes and some with just a single X, known as chromosome Y mosaicism. This results in a wide range of male/female genitalia that are not typically, or clearly, male or female. Children with this disorder may have one or two gonads which may be undescended and/or not easy to identify as typical testicles.

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Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: 1/29/2019 3:21:13 PM