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    Topic review

    HESX1 Gene

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    (This entry belongs to Entry Collection "MedlinePlus ")

    Definition

    HESX homeobox 1

    1. Introduction

    The HESX1 gene provides instructions for producing a protein that regulates the activity of other genes. On the basis of this action, the HESX1 protein is called a transcription factor. The HESX1 gene is part of a family of homeobox genes, which act during early embryonic development to control the formation of many body structures.

    The HESX1 protein plays an important role in early brain development. In particular, it is essential for the formation of the pituitary, which is a gland at the base of the brain that produces several hormones. The HESX1 protein is also necessary for the development of structures at the front of the brain (the forebrain), including the nerves that carry visual information from the eyes to the brain (optic nerves).

    The HESX1 protein interacts with other proteins, including the protein produced from the PROP1 gene, during embryonic development. Both the HESX1 protein and the PROP1 protein bind to DNA and control the activity of other genes. The HESX1 protein turns off (represses) genes, while the PROP1 protein turns on (activates) genes. These proteins work together to coordinate the development of certain parts of the brain.

    2. Health Conditions Related to Genetic Changes

    2.1. Septo-Optic Dysplasia

    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.

    2.2. Other Disorders

    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.

    3. Other Names for This Gene

    • ANF

    • CPHD5

    • HESX1_HUMAN

    • homeobox, ES cell expressed 1

    • Rathke pouch homeobox

    • RPX

    This entry is adapted from https://medlineplus.gov/genetics/gene/hesx1

    References

    1. Brickman JM, Clements M, Tyrell R, McNay D, Woods K, Warner J, Stewart A,Beddington RS, Dattani M. Molecular effects of novel mutations in Hesx1/HESX1associated with human pituitary disorders. Development. 2001 Dec;128(24):5189-99.
    2. Carvalho LR, Woods KS, Mendonca BB, Marcal N, Zamparini AL, Stifani S,Brickman JM, Arnhold IJ, Dattani MT. A homozygous mutation in HESX1 is associatedwith evolving hypopituitarism due to impaired repressor-corepressor interaction. J Clin Invest. 2003 Oct;112(8):1192-201.
    3. Dattani MT, Martinez-Barbera JP, Thomas PQ, Brickman JM, Gupta R, MårtenssonIL, Toresson H, Fox M, Wales JK, Hindmarsh PC, Krauss S, Beddington RS, Robinson IC. Mutations in the homeobox gene HESX1/Hesx1 associated with septo-opticdysplasia in human and mouse. Nat Genet. 1998 Jun;19(2):125-33.
    4. Dattani MT, Robinson IC. HESX1 and Septo-Optic Dysplasia. Rev Endocr MetabDisord. 2002 Dec;3(4):289-300. Review.
    5. Kato Y, Kimoto F, Susa T, Nakayama M, Ishikawa A, Kato T. Pituitaryhomeodomain transcription factors HESX1 and PROP1 form a heterodimer on theinverted TAAT motif. Mol Cell Endocrinol. 2010 Feb 5;315(1-2):168-73. doi:10.1016/j.mce.2009.10.006.
    6. McNay DE, Turton JP, Kelberman D, Woods KS, Brauner R, Papadimitriou A, KellerE, Keller A, Haufs N, Krude H, Shalet SM, Dattani MT. HESX1 mutations are anuncommon cause of septooptic dysplasia and hypopituitarism. J Clin EndocrinolMetab. 2007 Feb;92(2):691-7.
    7. Sobrier ML, Maghnie M, Vié-Luton MP, Secco A, di Iorgi N, Lorini R, Amselem S.Novel HESX1 mutations associated with a life-threatening neonatal phenotype,pituitary aplasia, but normally located posterior pituitary and no optic nerveabnormalities. J Clin Endocrinol Metab. 2006 Nov;91(11):4528-36.
    8. Sobrier ML, Netchine I, Heinrichs C, Thibaud N, Vié-Luton MP, Van Vliet G,Amselem S. Alu-element insertion in the homeodomain of HESX1 and aplasia of theanterior pituitary. Hum Mutat. 2005 May;25(5):503.
    9. Tajima T, Hattorri T, Nakajima T, Okuhara K, Sato K, Abe S, Nakae J, FujiedaK. Sporadic heterozygous frameshift mutation of HESX1 causing pituitary and opticnerve hypoplasia and combined pituitary hormone deficiency in a Japanese patient.J Clin Endocrinol Metab. 2003 Jan;88(1):45-50.
    10. Thomas PQ, Dattani MT, Brickman JM, McNay D, Warne G, Zacharin M, Cameron F,Hurst J, Woods K, Dunger D, Stanhope R, Forrest S, Robinson IC, Beddington RS.Heterozygous HESX1 mutations associated with isolated congenital pituitaryhypoplasia and septo-optic dysplasia. Hum Mol Genet. 2001 Jan 1;10(1):39-45.
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