Tumor necrosis factor receptor-associated periodic syndrome (TRAPS)
Also known as:
- autosomal dominant periodic fever with amyloidosis
- benign autosomal dominant familial periodic fever
- familial hibernian fever
- TNF receptor-associated periodic syndrome
Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a rare multisystem genetic disorder characterized by unexplained periodic episodes or attacks of fever associated with additional symptoms including muscle pain (myalgia), abdominal pain, headaches and skin rashes. The specific symptoms can vary greatly from one person to another. The duration of the characteristic episodes can also vary, lasting anywhere from a couple days to one week to more than one month. Onset is usually during infancy or childhood. TRAPS is caused by mutations of the tumor necrosis factor receptor-1 (TNFRSF1A) gene that encodes the 55-kDa receptor for TNF.
Signs & Symptoms
The specific symptoms associated with TRAPS vary from one person to another. Nearly all affected individuals will develop recurrent episodes of high-grade fever, pain and inflammation. However, some individuals may only develop fever or only fever and abdominal pain. The duration of the episodes varies, but they usually last more than one week. Some individuals may experience constant inflammation.
Characteristic febrile episodes may also be accompanied by chills, abdominal pain, headaches, joint pain (arthralgia), chest pain, and muscle pain (myalgia), stiffness and tightness. Abdominal pain may be associated with nausea, vomiting, and diarrhea or constipation. Chest pain is caused by inflammation of the thin covering (pleura) that lines the lungs (pleuritis). In some cases, muscle pain is severe.
Muscle pain may be associated with skin lesions, specifically tender, warm, reddish (erythematous), raised plaques. Skin lesions develop during a febrile episode and they move from the proximal toward distal sites of the body. Skin lesions may last anywhere from a few days to three weeks. Skin lesions associated with TRAPS usually begin as tiny bumps (macules or papules) that spread and come together to form larger lesions (plaques).
When muscle pain (myaligia) underlies skin lesions, it also moves (migrates) following skin lesions. As muscle pain progresses, different joints and muscle groups become involved. Although joint pain occurs, arthritis rarely develops.
Individuals with TRAPS may also develop painful inflammation of the delicate membranes that line the inside of the eyelids (conjunctivitis). This may occur with or without swelling of the eyelids (periorbital edema). Additional symptoms that have been reported in males with TRAPS include testicular pain and a higher rate of inguinal hernia than is found in the general population. Inguinal hernia is a condition in which a portion of the intestines protrudes through a tear in the lower abdominal wall.
A serious complication that occurs in approximately 10-15 percent of TRAPS cases is amyloidosis, a condition in which specialized proteins called amyloids abnormally accumulate in various tissues and organs of the body. For example, amyloid may accumulate in the kidneys, impairing kidney function and potentially causing life-threatening complications such as kidney failure. Although the kidneys are most often affected, numerous other organs can potentially become involved.
TRAPS can occur randomly due to a spontaneous genetic change (i.e., new mutation) or it may be inherited as an autosomal dominant trait (a mutation that is received either from the father or the mother).
Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50 percent for each pregnancy regardless of the gender of the resulting child.
The TNFRSF1A gene is located on the short arm (p) of chromosome 12 (12p13.2). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 12p13.2” refers to band 13.2 on the short arm of chromosome 12. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
The TNFRSF1A gene contains instructions for creating (encoding) a specialized protein known as tumor necrosis factor receptor-1 (TNFR1, p55, CD120a). TNFR1 is found on the surface of most cells of the body and serves as a receptor for tumor necrosis factor (TNF). TNF is a protein that helps defend the body against infection and foreign substances. Specifically TNF stimulates the body’s inflammatory response to infection. TNFR1 can receive and send signals that set off an inflammatory response within the body. These signals can be turned off when the TNF receptor detaches from the surface of the cell (a normal process called “shedding”). The loose receptors soak up excess TNF before it reaches cells, thereby preventing the signaling for the body’s inflammatory response. Mutations of the TRNFSF1A gene result in defective TNFR1 that cannot properly perform its normal functions. Defective TRNF1 allows for unchecked signaling of TNF, which causes an excessive inflammatory response by the body. The exact process by which defective TRNF1 results in TRAPS is under investigation.
The characteristic episodes of TRAPS may be triggered or worsened due to stress, minor trauma and exercise. However, no specific trigger is necessary for the development of episodes.
TRAPS was first described in the medical literature in 1982 in a large Irish family and initially termed familial Hibernian fever. The name was later changed when numerous individuals from other ethnic groups were identified to have mutations in the same gene, namely TNFRSF1A. TRAPS has been reported in individuals of many different ethnic groups, although initially many reported patients were of Scottish and Irish heritage. The exact incidence of the disorder is unknown, but there are couple of hundred of cases reported in the literature. TRAPS is a rare disease that often goes undiagnosed or misdiagnosed making it difficult to determine the disorder’s true frequency in the general population.
Ivona Aksentijevich, MD, National Human Genome Research Institute, National Institutes of Health
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