Sexual Health Q&A

What causes disorders of sex development (DSDs)?

Disorders of sex development may be caused by genetic or hormonal problems that occur during fetal development.

When an egg is fertilized, the resulting embryo has genetic material from each parent in the form of chromosomes. Genes, which provide the details of an organism’s development, reside on chromosomes.

Typically, the embryo receives an X chromosome from the mother and either an X or a Y chromosome from the father. These chromosomes determine whether a fetus will become a girl or a boy. Typically, girls have 2 X chromosomes and boys have an XY combination. The Y chromosome contains genes for the development of male reproductive organs, like the testes and penis.

Sometimes, there is a problem with one of the chromosomes. For example, a Y chromosome might signal that an embryo will become a boy, but the relevant genes on the chromosome might not work properly or they might not be present at all. As a result, his reproductive organs may not be fully developed.

DSDs can also result from hormonal problems. When a fetus develops, hormones typically help trigger maleness or femaleness. But if the fetus cannot produce the hormones – or respond properly to hormones – the baby may be born with a DSD.