HESX1

MedlinePlus Genetics provides information about Combined pituitary hormone deficiency

At least five mutations in the HESX1 gene have been identified in people with septo-optic dysplasia. Some of these mutations change single DNA building blocks (base pairs) in the HESX1 gene, while others insert or delete genetic material in the gene. Mutations in this gene alter the function of the HESX1 protein, for example by preventing it from binding to DNA and repressing the activity of other genes. HESX1 gene mutations disrupt the formation and early development of the pituitary gland, optic nerves, and other brain structures. These abnormalities of brain development lead to the characteristic features of septo-optic dysplasia.

Studies suggest that mutations in the HESX1 gene are a rare cause of septo-optic dysplasia.

More than a dozen HESX1 gene mutations have been found to cause underdevelopment (hypoplasia) of the pituitary gland in people without the other characteristic features of septo-optic dysplasia. Pituitary hypoplasia leads to a shortage of hormones needed for growth, reproduction, and other critical body functions. Affected individuals may also have signs and symptoms affecting other parts of the body, including genital abnormalities, vision impairment, distinctive facial features, and extra (supernumerary) fingers.

Mutations in the HESX1 gene lead to the production of a defective or nonfunctional HESX1 protein, which disrupts the formation of the pituitary gland during critical stages of embryonic development. Some mutations prevent the HESX1 protein from binding to DNA and repressing the activity of other genes. Other mutations prevent the HESX1 protein from interacting with the PROP1 protein to coordinate brain development. It is unclear how mutations in the HESX1 gene can cause signs and symptoms affecting other parts of the body.