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X-linked congenital adrenal hypoplasia

What is X-Linked Congenital Adrenal Hypoplasia?

X-linked congenital adrenal hypoplasia (XLCAH), is a disease caused by mutations in the NR0B1 gene and primarily affects males. This disorder causes the glands located above each kidney (adrenal glands) to not produce important chemicals called hormones. When these hormones are not produced properly, the body cannot retain enough sodium (salt). This is commonly called "salt wasting" and it can lead to serious illness with dehydration, vomiting, diarrhea, failure to thrive, heart rhythm abnormalities (arrhythmias), and shock. If not recognized and properly treated, a salt wasting crisis can be fatal.

XLCAH can also lead to a lack of sex hormones produced by the adrenal glands called hypogonadotropic hypogonadism. This lack of sex hormones can cause males with CAH to have smaller than average sex organs, undescended testes, delayed or incomplete puberty and fertility problems.

Most commonly, affected boys will show signs of the disease from the first few weeks of life to early childhood, but some later-onset cases have been reported. The age of onset and severity of symptoms can be variable, even within the same family.

This is an X-linked disease meaning that the NR0B1 gene is on the X-chromosome. Males have just one copy of the X-chromosome and NR0B1 gene while females have two copies. Because they only have one copy of the gene, males who carry a mutation in that gene are affected by the condition while female carriers still have one normal (working) copy of the gene. Because of this, most female carriers do not have symptoms, however, in rare cases female carriers have been reported with adrenal insufficiency or hypogonadotropic hypogonadism.

How common is X-Linked Congenital Adrenal Hypoplasia?

This is a rare disorder. Studies estimate that more than 1 in 600,000 males will have XLCAH, but the true global incidence is unknown. Other presentations of XLCAH may not be recognized as of yet.

How is X-Linked Congenital Adrenal Hypoplasia treated?

Currently, there is no cure for XLCAH. However, treatments are available for the symptoms. Patients benefit from taking hormone replacement medications to restore and maintain the right balance of hormones in the body; most patients will need to take hormone medications for the rest of their lives. A multidisciplinary team of physicians, including an endocrinologist, will need to monitor the hormone levels to determine medication dosage, medication side effects, growth, and sexual development of patients with this condition. The endocrinologist will carefully monitor sex hormones near puberty and supplement hormones if puberty is delayed or not progressing as expected.

Once the condition is diagnosed, illness caused by salt-wasting should be treated in a hospital where the imbalances can be monitored and corrected.

What is the prognosis for a person with X-Linked Congenital Adrenal Hypoplasia?

With early diagnosis and proper medication management, most individuals with XLCAH will have a normal life expectancy. Early death can occur during periods of significant sodium loss (salt crises) if medication dosage is not adequately adjusted, especially during times of illness or trauma. Problems with sexual development and infertility are monitored by physicians on an ongoing basis.