Blau syndrome | |
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Other names | Arthrocutaneouveal granulomatosis [1] |
Coarse facial features in a boy with Blau syndrome | |
Specialty | Dermatology |
Blau syndrome is an autosomal dominant genetic inflammatory disorder which affects the skin, eyes, and joints. It is caused by a mutation in the NOD2 (CARD15) gene. [2] and is classified as an inborn error of immunity. [3] Symptoms usually begin before the age of four, and the disease manifests as early onset cutaneous sarcoidosis, granulomatous arthritis, and uveitis.
Blau syndrome classically presents in early childhood as a triad of granulomatous dermatitis, arthritis, and uveitis. Arthritis typically affects peripheral joints mainly wrists, knees, ankles, and proximal interphalangeal (PIP) joints of the hands. Tenosynovitis is another characteristic feature; tendon sheaths appear enlarged on examination; most often the extensor tendons of the wrist, the pes anserinus, peroneal, and flexor tibialis tendon sheaths are affected. Skin rash is typically the first symptom to appear, usually in the first year of life. The most frequent appearance is that of an erythematous maculo-micropapular fine scaly rash on the trunk and extremities. Uveitis presents as an insidious granulomatous iridocyclitis with posterior uveitis in 60–80% of patients. [4]
The discovery that the gene defect in Blau syndrome involves the CARD15/NOD2 gene has sparked investigation into its function as part of the innate immune system. The innate immune system recognizes pathogen-associated molecular patterns, including bacterial polysaccharides such as muramyl dipeptide, via its pattern recognition receptors, such as NOD2, to induce signaling pathways that activate cytokine responses and protect the organism. In Blau syndrome, the genetic defect seems to lead to overactivation and poor control of the inflammatory response leading to widespread granulomatous inflammation and tissue damage. [5] [6]
The diagnosis of Blau syndrome is made by the presentation of classical clinical features and can be confirmed by genetic testing and biopsy. Laboratory and imaging studies can be supportive but are usually not diagnostic. [7]
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In 1981, Malleson et al. reported a family that had autosomal dominant synovitis, camptodactyly, and iridocyclitis. [8] One member died of granulomatous arteritis of the heart and aorta.
In 1982, Rotenstein reported a family with granulomatous arteritis, rash, iritis, and arthritis transmitted as an autosomal dominant trait over three generations. [9]
In 1985, Edward Blau, a pediatrician in Marshfield, Wisconsin, reported a family that over four generations had granulomatous inflammation of the skin, eyes and joints. The condition was transmitted as an autosomal dominant trait. In the same year Jabs et al. reported a family that over two generations had granulomatous synovitis, uveitis and cranial neuropathies. [10]
Then in 1990 Pastores et al. reported a kindred with a phenotype very similar to what Blau described and suggested that the condition be called Blau syndrome. They also pointed out the similarities in the families noted above to Blau syndrome but also pointed out the significant differences in the phenotypes. [11]
In 1996 Tromp et al. conducted a genome wide search using affected and non-affected members of the original family. A marker, D16S298, gave a maximum logarithm of odds score of 3.75 and put the Blau syndrome susceptibility locus within the 16p12-q21 interval. Hugot et al. found a susceptibility locus for Crohn disease, a granulomatous inflammation of the bowel, on chromosome 16 close to the locus for BS. Based on the above information Blau suggested in 1998 that the genetic defect in Blau syndrome and Crohn disease might be the same or similar.
Finally in 2001 Miceli-Richard et al. found the defect in Blau syndrome to be in the nucleotide-binding domain of CARD15/NOD2. They commented in their article that mutations in CARD15 had also been found in Crohn disease. Confirmation of the defect in Blau syndrome being in the CARD15 gene was made by Wang et al. in 2002 using the Blau syndrome family and others. [10]
Sarcoidosis is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly affected are the eyes, liver, heart, and brain, though any organ can be affected. The signs and symptoms depend on the organ involved. Often, no symptoms or only mild symptoms are seen. When it affects the lungs, wheezing, coughing, shortness of breath, or chest pain may occur. Some may have Löfgren syndrome with fever, large lymph nodes, arthritis, and a rash known as erythema nodosum.
Familial Mediterranean fever (FMF) is a hereditary inflammatory disorder. FMF is an autoinflammatory disease caused by mutations in the Mediterranean fever (MEFV) gene, which encodes a 781–amino acid protein called pyrin. While all ethnic groups are susceptible to FMF, it usually occurs in people of Mediterranean origin—including Sephardic Jews, Mizrahi Jews, Ashkenazi Jews, Assyrians, Armenians, Azerbaijanis, Druze, Levantines, Kurds, Greeks, Turks and Italians.
Chronic granulomatous disease (CGD), also known as Bridges–Good syndrome, chronic granulomatous disorder, and Quie syndrome, is a diverse group of hereditary diseases in which certain cells of the immune system have difficulty forming the reactive oxygen compounds used to kill certain ingested pathogens. This leads to the formation of granulomas in many organs. CGD affects about 1 in 200,000 people in the United States, with about 20 new cases diagnosed each year.
Uveitis is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and includes the iris, ciliary body, and choroid. Uveitis is described anatomically, by the part of the eye affected, as anterior, intermediate or posterior, or panuveitic if all parts are involved. Anterior uveitis (iridocyclitis) is the most common, with the incidence of uveitis overall affecting approximately 1:4500, most commonly those between the ages of 20–60. Symptoms include eye pain, eye redness, floaters and blurred vision, and ophthalmic examination may show dilated ciliary blood vessels and the presence of cells in the anterior chamber. Uveitis may arise spontaneously, have a genetic component, or be associated with an autoimmune disease or infection. While the eye is a relatively protected environment, its immune mechanisms may be overcome resulting in inflammation and tissue destruction associated with T-cell activation.
Connective tissue disease, also known as connective tissue disorder, or collagen vascular diseases, refers to any disorder that affects the connective tissue. The body's structures are held together by connective tissues, consisting of two distinct proteins: elastin and collagen. Tendons, ligaments, skin, cartilage, bone, and blood vessels are all made of collagen. Skin and ligaments contain elastin. The proteins and the body's surrounding tissues may suffer damage when these connective tissues become inflamed.
Leflunomide, sold under the brand name Arava among others, is an immunosuppressive disease-modifying antirheumatic drug (DMARD), used in active moderate-to-severe rheumatoid arthritis and psoriatic arthritis. It is a pyrimidine synthesis inhibitor that works by inhibiting dihydroorotate dehydrogenase.
Neonatal-onset multisystem inflammatory disease is a rare genetic periodic fever syndrome which causes uncontrolled inflammation in multiple parts of the body starting in the newborn period. Symptoms include skin rashes, severe arthritis, and chronic meningitis leading to neurologic damage. It is one of the cryopyrin-associated periodic syndromes.
Type III Collagen is a homotrimer, or a protein composed of three identical peptide chains (monomers), each called an alpha 1 chain of type III collagen. Formally, the monomers are called collagen type III, alpha-1 chain and in humans are encoded by the COL3A1 gene. Type III collagen is one of the fibrillar collagens whose proteins have a long, inflexible, triple-helical domain.
Nucleotide-binding oligomerization domain-containing protein 2 (NOD2), also known as caspase recruitment domain-containing protein 15 (CARD15) or inflammatory bowel disease protein 1 (IBD1), is a protein that in humans is encoded by the NOD2 gene located on chromosome 16. NOD2 plays an important role in the immune system. It recognizes bacterial molecules (peptidoglycans) and stimulates an immune reaction.
Anti-Saccharomyces cerevisiae antibodies (ASCAs) are antibodies against antigens presented by the cell wall of the yeast Saccharomyces cerevisiae. These antibodies are directed against oligomannose sequences α-1,3 Man n. ASCAs and perinuclear antineutrophil cytoplasmic antibodies (pANCAs) are the two most useful and often discriminating biomarkers for colitis. ASCA tends to recognize Crohn's disease more frequently, whereas pANCA tend to recognize ulcerative colitis.
Chronic recurrent multifocal osteomyelitis (CRMO) is a rare condition (1:1,000,000), in which the bones have lesions, inflammation, and pain. It is called multifocal because it can appear in different parts of the body, primarily bones, and osteomyelitis because it is very similar to that disease, although CRMO appears to be without any infection.
The nucleotide-binding oligomerization domain-like receptors, or NOD-like receptors (NLRs), are intracellular sensors of pathogen-associated molecular patterns (PAMPs) that enter the cell via phagocytosis or pores, and damage-associated molecular patterns (DAMPs) that are associated with cell stress. They are types of pattern recognition receptors (PRRs), and play key roles in the regulation of innate immune response. NLRs can cooperate with toll-like receptors (TLRs) and regulate inflammatory and apoptotic response.
AA amyloidosis is a form of amyloidosis, a disease characterized by the abnormal deposition of fibers of insoluble protein in the extracellular space of various tissues and organs. In AA amyloidosis, the deposited protein is serum amyloid A protein (SAA), an acute-phase protein which is normally soluble and whose plasma concentration is highest during inflammation.
Palisaded neutrophilic and granulomatous dermatitis (PNGS) is usually associated with a well-defined connective tissue disease, lupus erythematosus or rheumatoid arthritis most commonly, and often presents with eroded or ulcerated symmetrically distributed umbilicated papules or nodules on the elbows.
Necrotizing vasculitis, also called systemic necrotizing vasculitis, is a general term for the inflammation of veins and arteries that develops into necrosis and narrows the vessels.
Cryopyrin-associated periodic syndrome (CAPS) is a group of rare, heterogeneous autoinflammatory disease characterized by interleukin 1β-mediated systemic inflammation and clinical symptoms involving skin, joints, central nervous system, and eyes. It encompasses a spectrum of three clinically overlapping autoinflammatory syndromes including familial cold autoinflammatory syndrome, the Muckle–Wells syndrome (MWS), and neonatal-onset multisystem inflammatory disease that were originally thought to be distinct entities, but in fact share a single genetic mutation and pathogenic pathway, and keratoendotheliitis fugax hereditaria in which the autoinflammatory symptoms affect only the anterior segment of the eye.
Enteropathic arthropathy commonly referred to as enteropathic arthritis, is a type of arthritis linked to Crohn's disease, ulcerative colitis, and chronic inflammatory bowel diseases.
Familial episodic pain syndrome, also known simply as FEPS, is a group of rare genetic peripheral neuropathies which are characterized by recurrent random episodes of intense pain which occur most often in the upper or lower parts of the body occurring in several members of the same family. They are often triggered by cold temperatures, physical exercise, fatigue, etc. It may or may not get better with age.
PMC 4136643. doi : 10.1186/1546-0096-12-33 .