When a child's gender is in question at birth, because genitals may not appear clearly male or female, the child is said to have atypical genitalia, also known as ambiguous genitalia. Atypical genitalia can be a traumatizing experience for parents.
Early in fetal development, the tissue that will become the gonads (ovaries or testes) is undifferentiated and has the potential to become either ovaries or testes, depending on the genetics of the fetus. Humans have 46 chromosomes in each cell of their bodies, or 23 pairs. The 23rd pair determines our gender; females have two X chromosomes, while males have one X and one Y chromosome. The chromosome complement in humans is written: 46, XX, normal female or 46, XY, normal male.
There is a gene located on the short arm (top half) of the Y chromosome, called "SRY," which, if present, will cause the undifferentiated gonad to become testes (indicating a male) around the sixth week of fetal life. At the same time, regression of what would have been the female reproductive tract occurs. As the testes produce testosterone, the phallus (penis), scrotum, and urethra form. Later, during the seventh to eighth month of the pregnancy, the testes will descend into the scrotum.
In the absence of the SRY gene, the gonad will differentiate into an ovary (indicating a female). Likewise, the female reproductive tract will continue to develop, forming the uterus and fallopian tubes. At the same time, regression of what would have become the male reproductive organs occurs.
Besides the SRY gene, certain hormones can influence the development of the sexual organs. These hormones are secreted during the early weeks of gestation and include the anti-mullarian hormone, testosterone hormone, and dihydrotestosterone, an active derivative of testosterone.
A variety of genetic and environmental factors may influence this development, leading to atypical genitalia. Ambiguous genitalia, as the term implies, may make determining the child's gender more difficult. Very few infants with atypical genitalia have genitals that are so ambiguous that a gender determination is not made at birth. Far more common are the following observations at birth:
There are a number of different causes of atypical genitalia, with the most common described below. The cause, in many cases, is not known and the disorder appears to occur by chance. Children who are born with atypical genitalia may fall into one of the following groups:
There are two primary causes of male pseudohermaphroditism:
This is called "androgen insensitivity syndrome," because male infants are not responsive to androgens (testosterone). Androgen insensitivity syndrome is inherited by a defect in the androgen receptor gene on the X chromosome, and the inheritance is therefore described as "X-linked recessive." Mothers who carry the gene have a 50/50 chance to have a son with androgen insensitivity syndrome, while daughters (of mothers who carry the gene) have a 50/50 chance to be carriers of the gene.
The enzyme 5-alpha reductase is deficient; therefore, it cannot carry out its task of converting testosterone into dihydrotestosterone (DHT), which is necessary for complete masculinization of a male fetus. A 5-alpha-reductase deficiency is inherited by an autosomal recessive gene, which means that each parent carries one copy of the gene and transmits it to the child. Carrier parents have a one in eight, or 12.5 percent, chance, with each pregnancy, to have an affected child since only males are affected.
There are a number of causes of female pseudohermaphroditism:
In some cases, the mother of a child with CAH can be given medications during pregnancy to lessen the effects of the enzyme deficiency, if the fetus is female.
Another type of CAH, called "salt-losing," is very serious and often lethal due to an electrolyte collapse in the newborn. Treatment is available if diagnosed early. Males and females are equally affected. There are other, more rare enzyme problems, which can result in CAH in either males or females.
There are a number of other syndromes in which atypical genitalia is one feature (characteristic) of the disorder, in addition to other features.
When a child's genitalia appear ambiguous at birth, your child's physician will conduct both a medical history and a physical examination of your child's external genitalia. The medical history will include the mother's health during pregnancy and a family history of any neonatal deaths or genital abnormalities. First, your child's physician will make a diagnosis of the underlying cause of the disorder. Diagnostic procedures may include a newborn screening test for CAH, hormonal studies, and a biopsy of the reproductive organs.
To determine the sex, your child's physicians will consider the following:
Sometimes, there is an increased risk for tumors in the gonads. Treatment for atyipcal genitalia depends of the type of the disorder, but will usually include corrective surgery to remove or create reproductive organs appropriate for the gender of the child. Treatment may also include hormone replacement therapy. Most important, the family should be involved early in the decision making of assigning the sex of the child, and long-term psychological support should be offered.
Making a correct determination of gender is important both for treatment purposes, as well as for the emotional well-being of the child. Some children born with atypical genitalia may have normal internal reproductive organs that allow them to live normal, fertile lives. However, others may experience reduced or absent fertility (difficulty or inability to conceive a child).
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