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X-linked adrenal hypoplasia congenita
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Reviewed April 2008
What is X-linked adrenal hypoplasia congenita?
X-linked adrenal hypoplasia congenita is a disorder that mainly affects males. It involves many hormone-producing (endocrine) tissues in the body, particularly a pair of small glands on top of each kidney called the adrenal glands. These glands produce a variety of hormones that regulate many essential functions in the body.
One of the main signs of this disorder is adrenal insufficiency, which occurs when the adrenal glands do not produce enough hormones. Adrenal insufficiency typically begins in infancy or childhood and can cause vomiting, difficulty with feeding, dehydration, extremely low blood sugar (hypoglycemia), and shock. If untreated, these complications are often life-threatening.
Affected males may also have a shortage of male sex hormones, which leads to underdeveloped reproductive tissues, undescended testicles (cryptorchidism), delayed puberty, and an inability to father children (infertility). Together, these characteristics are known as hypogonadotropic hypogonadism.
The onset and severity of these signs and symptoms can vary, even among affected members of the same family.
How common is X-linked adrenal hypoplasia congenita?
X-linked adrenal hypoplasia congenita is estimated to affect 1 in 12,500 newborns.
What genes are related to X-linked adrenal hypoplasia congenita?
Mutations in the NR0B1 gene cause X-linked adrenal hypoplasia congenita. The NR0B1 gene provides instructions to make a protein called DAX1. This protein plays an important role in the development and function of several hormone-producing (endocrine) tissues including the adrenal glands, two hormone-secreting glands in the brain (the hypothalamus and pituitary), and the gonads (ovaries in females and testes in males). The hormones produced by these glands control many important body functions.
Some NR0B1 mutations result in the production of an inactive version of the DAX1 protein, while other mutations delete the entire gene. The resulting shortage of DAX1 disrupts the normal development and function of hormone-producing tissues in the body. The signs and symptoms of adrenal insufficiency and hypogonadotropic hypogonadism occur when endocrine glands do not produce the right amounts of certain hormones.
Read more about the NR0B1 gene.
How do people inherit X-linked adrenal hypoplasia congenita?
This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
In X-linked recessive inheritance, a female with one mutated copy of the gene in each cell is called a carrier. She can pass on the altered gene, but usually does not experience signs and symptoms of the disorder. In rare cases, however, females who carry a NR0B1 mutation may experience adrenal insufficiency or signs of hypogonadotropic hypogonadism such as underdeveloped reproductive tissues, delayed puberty, and an absence of menstruation.
Where can I find information about diagnosis or management of X-linked adrenal hypoplasia congenita?
These resources address the diagnosis or management of X-linked adrenal hypoplasia congenita and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about X-linked adrenal hypoplasia congenita?
You may find the following resources about X-linked adrenal hypoplasia congenita helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for X-linked adrenal hypoplasia congenita?
What if I still have specific questions about X-linked adrenal hypoplasia congenita?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding X-linked adrenal hypoplasia congenita?
adrenal cortex ; adrenal glands ; carrier ; cell ; chromosome ; cryptorchidism ; dehydration ; gene ; hormone ; hypoglycemia ; hypogonadism ; hypogonadotropic ; hypoplasia ; hypothalamus ; infertility ; inheritance ; inherited ; kidney ; menstruation ; mutation ; protein ; puberty ; recessive ; sex chromosomes ; shock ; testes ; testicles ; wasting ; X-linked recessive
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (11 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.