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Disorders of Sex Development for Boys

Over the last couple of months, we’ve looked at disorders of sex development (DSDs) here on the Sex Health Matters blog. DSDs are congenital conditions (present at birth) that affect a baby’s reproductive organs. Sometimes, the organs are absent or not fully developed. Or, a baby might have both male and female organs.

There are many different types of DSDs and we discussed some of them in this recent post. We’ve also talked about vaginal agenesis, a condition in which girls are born without a properly formed vagina.

Today, we’re going to cover three types of DSDs that affect boys: Hypospadias, Klinefelter syndrome, and micropenis.

DSDs – Some Background

First, however, let’s do a little review of how DSDs can form.

When a human fetus develops, it has genetic material from both the mother and father. Each parent contributes a sex chromosome. Females have two X chromosomes (XX) and males have an X and a Y chromosome (XY).

These chromosomes, and the genes located on them, provide the “road map” for genetic males and females. For example, they dictate whether an embryo develops testes or ovaries.

But sometimes, there are problems. An embryo may have an extra chromosome or a defective gene that interferes with hormones. These issues are at the root of DSDs. There are also times when doctors really aren’t sure exactly why a DSD occurs.


Hypospadias affects the position of the urethra – the tube that allows urine to exit the body. Normally, the opening of the urethra is found at the tip of the penis. But for boys with hypospadias, the opening might be on the underside of the penis, at the base, or on the scrotum (the sac that contains the testes). Most of the time, the opening is somewhere near the tip.

Usually, hypospadias is discovered when a newborn baby is still in the hospital. Milder cases might not be found until later, however.

Hypospadias can be corrected with surgery. The Mayo Clinic suggests that this take place when the baby is between four and twelve months old, but it can be done in adulthood as well.

With treatment, hypospadias has a good prognosis. Most boys have no problems with urination and no issues with sexual activity when they get older.

Left untreated, however, a boy can have trouble using the toilet. Men with hypospadias may develop erectile dysfunction (ED), the inability to get and keep an erection firm enough for sex.


As the name suggests, “micropenis” refers to a small penis. Doctors stretch the penis to its full length to measure it. If the measurement is 0.75 inches or shorter, the child is diagnosed with a micropenis.

A micropenis may happen on its own or it might be part of another DSD. Often, it is caused by hormonal problems that originate in the pituitary gland or in a part of the brain called the hypothalamus.

The condition is usually treated with testosterone therapy, which can help the penis grow. Other hormones might also be used, especially if the child has hormonal deficiencies. In rare cases, gender reassignment surgery is considered.

Most boys with a micropenis do well with testosterone treatment and have normal penile function when they grow up. However, many are infertile.

Klinefelter Syndrome

Klinefelter syndrome occurs when a child has a Y chromosome and more than one X chromosome. In other words, his genetic makeup might be XXY instead of XY. While Klinefelter syndrome involves chromosomes, it is not inherited. Instead, it happens by chance in a parent’s reproductive cell. Sometimes it happens when a cell does not divide correctly.

The extra X chromosome makes it more difficult for male characteristics to form. As a result, boys with Klinefelter syndrome have smaller testes that don’t make the normal amount of testosterone, the male sex hormone. Boys may have late puberty or not reach puberty at all. They might have less facial hair and body hair. Breast development, like that of a female, is also possible and there is an increased risk of breast cancer. Many boys with Klinefelter syndrome grow up to be infertile, but some can father children through artificial reproductive technologies.

Learning disabilities and delayed speech and language development are also common.

When children have more than one extra X chromosome, they are said to have a variant of Klinefelter syndrome. In these rare cases, the typical symptoms are more severe, worsening with each additional X chromosome present.

It’s also possible for boys with Klinefelter syndrome to have an extra X chromosome in only some cells. This is called mosaic Klinefelter syndrome.

Treatment for Klinefelter syndrome usually includes hormonal therapy, speech and behavioral therapy, physical and occupational therapy, and counseling. Some men who develop breasts decide to have them surgically removed.

Coping with any type of DSD can be tough for families. A child’s doctor can suggest resources for further information and support.

Print this article or view it as a PDF file here: Disorders of Sex Development for Boys


Accord Alliance


Genetics Home Reference

“Klinefelter syndrome”

(Reviewed: January 2013)

Mayo Clinic


(January 22, 2011)

Medscape Reference

Chen, Harold, MD, MS, FAAP, FACMG

“Klinefelter syndrome”

(Updated: February 22, 2013)

Vogt, Karen S.


(Updated: April 18, 2013)

University of Rochester Medical Center