Meyahealth
HomeGeneticsGeneMRAP gene
Back to Gene
MRAP gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MRAP gene

The MRAP gene provides instructions for making a protein essential for the activation and transport of the ACTH receptor, which regulates critical hormone production in the body.

Normal Function

The MRAP gene provides instructions for making a protein called melanocortin-2 receptor accessory protein (MRAP). This protein transports another protein, called the melanocortin-2 receptor (or more commonly the adrenocorticotropic hormone [ACTH] receptor), from the interior of the cell to the cell surface. Specifically, the MRAP protein transports the ACTH receptor from a cell structure called the endoplasmic reticulum (ER), which is involved in protein processing and transport, to the cell membrane so that the receptor can function. The MRAP protein is also needed to turn on (activate) the ACTH receptor.

At the cell membrane, the activated ACTH receptor attaches (binds) to ACTH, which triggers the production of a group of hormones called glucocorticoids. These hormones, which include cortisol and corticosterone, aid in immune system function, play a role in maintaining normal blood sugar (glucose) levels, help trigger nerve cell signaling in the brain, and serve many other purposes in the body.

Health Conditions Related to Genetic Changes

Familial glucocorticoid deficiency

At least 13 mutations in the MRAP gene have been found to cause familial glucocorticoid deficiency. This condition is characterized by potentially life-threatening low blood glucose (hypoglycemia), recurrent infections, and skin coloring darker than that of other family members (hyperpigmentation). MRAP gene mutations account for approximately 20 percent of cases of this condition.

Most of these mutations lead to the production of a protein that cannot interact with the ACTH receptor and so is unable to transport it out of the ER to the cell membrane. As a result, the ACTH receptor is not at the cell surface where it is needed to bind to ACTH. Without the binding of the ACTH receptor to its hormone, there is no signal to trigger the adrenal glands to produce glucocorticoids. A shortage of these hormones impairs blood glucose regulation, immune system function, and other cellular functions, leading to the signs and symptoms of familial glucocorticoid deficiency.

Other Names for This Gene

  • B27
  • C21orf61
  • FALP
  • fat cell-specific low molecular weight protein
  • fat tissue-specific low MW protein
  • GCCD2
  • melanocortin-2 receptor accessory protein
  • MRAP_HUMAN

Frequently Asked Questions

The diagnosis usually starts with a blood test measuring cortisol and ACTH after a short overnight fast. If cortisol is low but ACTH is high, an ACTH stimulation test is performed. Genetic testing—typically a targeted MRAP gene panel or whole exome sequencing—will identify pathogenic variants that prevent MRAP from transporting the ACTH receptor to the cell surface.
The mainstay is lifelong glucocorticoid replacement therapy, usually oral hydrocortisone or prednisone, dosed to mimic the body’s natural rhythm. Patients may also need mineralocorticoid replacement if aldosterone production is affected. Regular monitoring of blood glucose, electrolytes, and growth is essential, and patients should be educated on stress dosing during illness or surgery.
Yes, first‑degree relatives can undergo genetic testing to determine if they carry the same MRAP variant. If they do not have symptoms, they may still be at risk for mild or late‑onset disease and should be monitored for signs of adrenal insufficiency. If they are mutation‑negative, they are not at risk for this specific condition, though other causes of adrenal insufficiency remain possible.
Early signs often include unexplained low blood sugar (hypoglycemia) that can cause shakiness, sweating, or fainting, recurrent infections that do not resolve quickly, and darker skin patches (hyperpigmentation) that are more pronounced than in other family members. If these occur, a pediatrician should consider checking cortisol levels and ACTH responsiveness.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ