DAX1 - Role in Disease

Role in Disease

X-linked adrenal hypoplasia congenita is caused by mutations in the NR0B1 gene. More than 90 NR0B1 mutations that cause X-linked adrenal hypoplasia congenita have been identified. Many of these mutations delete all or part of the NR0B1 gene, preventing the production of DAX1 protein. Some mutations cause the production of an abnormally short protein. Other mutations cause a change in one of the building blocks (amino acids) of DAX1. These mutations are thought to result in a misshapen, nonfunctional protein. Loss of DAX1 function leads to adrenal insufficiency and hypogonadotropic hypogonadism, which are the main characteristics of this disorder.

Duplication of genetic material on the X chromosome in the region that contains the NR0B1 gene can cause a condition called dosage-sensitive sex reversal. The extra copy of the NR0B1 gene prevents the formation of male reproductive tissues. People who have this duplication usually appear to be female, but are genetically male with both an X and a Y chromosome.

In some cases, genetic material is deleted from the X chromosome in a region that contains several genes, including NR0B1. This deletion results in a condition called adrenal hypoplasia congenita with complex glycerol kinase deficiency. In addition to the signs and symptoms of adrenal hypoplasia congenita, individuals with this condition may have elevated levels of lipids in their blood and urine and may have problems regulating blood sugar levels. In rare cases, the amount of genetic material deleted is even more extensive and affected individuals also have Duchenne muscular dystrophy.