Mixed connective tissue disease

Last updated
Mixed connective tissue disease
Other namesSharp's syndrome [1]
Specialty Immunology, rheumatology   OOjs UI icon edit-ltr-progressive.svg
Differential diagnosis CPT2.

Mixed connective tissue disease, commonly abbreviated as MCTD, is an autoimmune disease characterized by the presence of elevated blood levels of a specific autoantibody, now called anti-U1 ribonucleoprotein (RNP), together with a mix of symptoms of systemic lupus erythematosus (SLE), scleroderma, and polymyositis. [2] The idea behind the "mixed" disease is that this specific autoantibody is also present in other autoimmune diseases such as systemic lupus erythematosus, polymyositis, scleroderma, etc. MCTD was characterized as an individual disease in 1972 by Sharp et al., [3] [4] and the term was introduced by Leroy [5] in 1980. [6]

Contents

It is sometimes said to be the same as undifferentiated connective tissue disease, [1] but other experts specifically reject this idea [7] because undifferentiated connective tissue disease is not necessarily associated with serum antibodies directed against the U1-RNP, and MCTD is associated with a more clearly defined set of signs/symptoms. [7]

Signs and symptoms

MCTD combines features of scleroderma, polymyositis, systemic lupus erythematosus, and rheumatoid arthritis [8] (with some sources adding myositis, dermatomyositis, and inclusion body myositis) [9] and is thus considered an overlap syndrome.

The initial clinical manifestations of MCTD usually are unspecific. They can consist of general malaise, arthralgias, myalgias, and fever. The specific signs to suspect this disease is the presence of positive antinuclear antibodies (ANA), specifically anti-RNP, associated with Raynaud's phenomenon. [4] Almost every organ can be affected by MCTD. [2] Raynaud's phenomenon is the most common presenting symptom seen in patients, with arthralgia and swollen hands being the second and third most common respectively. [3] With patients that meet full criteria for MCTD, arthritis is the most common symptom with Raynaud's, swollen hands, leukopenia/lymphopenia, and heartburn following in descending order. A 2016 epidemiological population based study found 3.6 years to be the average amount of time from the first manifestations of the disease until all the criteria for diagnosis were met. [3]

Manifestations include:

Genetics

The contribution of genetics toward developing MCTD is unknown. [10] Family members have been known to develop MCTD suggesting that genetics may play a role in MCTD, however most cases present individually. [11] As MCTD can present with comorbid connective tissue diseases there must be a genetic link, however it has not yet been discovered. DNA methylation may affect the as yet unknown genetic risks of this disease as patients with MCTD have decreased DNA methylation levels in opposition to their healthy counterparts.[ citation needed ]

Pathophysiology

MCTD is an autoimmune disorder. Anti-RNP antibodies develop against RNP when RNP is found outside of the nucleus. RNP is immunologically protected due to its location, however if a cell dies and RNP is no longer contained in the nucleus and thus unprotected, the immune system can respond by forming antibodies due to cellular mimicry. Risk to develop MCTD can increase if the body has been exposed to molecules or viruses with a similar structure to RNP in the past. [12]

There are currently no known environmental factors or triggers contributing to MCTD.[ citation needed ]It has been associated with HLA-DR4. [13]

Diagnosis

Distinguishing laboratory characteristics are a positive, speckled anti-nuclear antibody and an anti-U1-RNP antibody. [14] [15]

After the original 1972 description of MCTD by Sharp, there was some controversy over whether MCTD was a distinct connective tissue disease; however, after four decades and more than 2000 publications, it seems that there is a consensus that MCTD should be considered a distinctive clinical entity, and is thus considered as such by the majority of rheumatologists, [16] though there is a subgroup of patients that could evolve in their disease course towards another connective tissue disease.

Although almost any organ can be affected by MCTD, there are various clinical manifestations that make it more likely to suspect the disease is MCTD over other connective tissue diseases: [2]

  1. Raynaud's phenomenon.
  2. Edematous hands and swollen fingers.
  3. Arthritis more severe than that of SLE.
  4. Pulmonary hypertension (does not need to be pulmonary fibrosis) differentiates MCTD from SLE and scleroderma.
  5. Anti-RNP antibodies in elevated levels, especially antibodies against protein 68 kD.
  6. Absence of severe renal or CNS disease.

Several criteria have been described to standardize the diagnosis of the disease, some of the most used being those of Alarcón-Segovia, although there are no universally accepted criteria. [17] [18] [19] Due to the wide range of signs and symptoms, there is no agreement on what the optimal criteria are for diagnosis. Even with a low anti-RNP antibody titer, a patient can show symptoms of MTD. The reverse is also possible: a patient with a high anti-RNP antibody titer can show no symptoms. [20] In general the criteria require the presence of high titres of anti-RNP antibodies, the presence of some characteristic signs of the disease – Raynaud or swollen hands/fingers – and the presence of some clinical manifestations of at least two other connective tissue diseases – SLE, scleroderma, polymyositis.[ citation needed ].

A. Serologic criteria:

Positive Anti-RNP at a titre> 1:1600 by hemagglutination

B. Clinical Criteria

1. Edema of the hands

2. Synovitis

3. Myositis

4. Raynaud's phenomenon

5. Acrosclerosis

MCTD is present with:

Criteria A together with 3 or more clinical criteria

–one of which must be synovitis or myositis–

It is often several years before sufficient signs and symptoms appear to make the diagnosis of MCTD, relative to the more sequential clinical manifestations of SLE, scleroderma, and polymyositis, so often, in the initial phases, the diagnosis most appropriate for patients is "undifferentiated connective tissue disease". [19]

If the patient has edematous hands and/or swollen fingers in conjunction with elevated titers of antinuclear antibodies, an elevated titre of anti-U1 RNP antibody is a good predictor of progressing to MCTD. [21] The presence of this specific antibody is sine qua non for the diagnosis of MCTD, [19] although its isolated presence does not guarantee that a patient has MCTD or will develop it. If the dominant autoantibodies are  antiDNAn, Sm, Scl70 or Ro, it is likely the patient will develop another connective disease distinct from MCTD. The clinical manifestations of MCTD appear correlated more intensely to the antibodies against protein A’ and 68 kD of the U1 RNP complex. The typical phenotype of MCTD also appears to be in part genetically determined, as patients with MCTD are associated with HLA-DR4 or HLA-DR2, meanwhile those with SLE are associated with HLA-DR3 and those with scleroderma are associated with HLA-DR5. [22]

SLE, scleroderma, and in MCTD have antibodies against anti-U1-snRNP at differing percentages. These antibodies are in most MCTD patients but are seen in only 30–35% of SLE and 2–14% of scleroderma patients, therefore they can help differentiate MCTD from other connective tissue disorders.  There are different haplotypes of SNRNP70 which due to their differences in patients with MCTD versus those with SLE or scleroderma help substantiate the claim that MCTD is a separate disease. The T-G-CT-G haplotype is more common in patients with MCTD, whereas the T-G-C-G haplotype is more commonly seen in scleroderma and SLE. [23]

Differential diagnosis includes CPT2.

Treatment

Although MCTD was originally described as a disease with a good treatment response to corticosteroids, the treatment of the disease is based on the specific manifestations and clinical complications, similar to how other signs and symptoms are treated in other connective tissue disease. [24] [25]

Standard

For arthritis, non-steroidal anti-inflammatories or low dose prednisone are usually used, which can be used in association with methotrexate or hydroxychloroquine. Temporomandibular joint arthritis has been shown to be successfully treated with condylar reconstruction using chondral grafts. [26] Higher doses of corticosteroids (0.25 to 1 mg/kg/day) are used in complications such as myositis, meningitis, pleuritis, pericarditis, myocarditis, interstitial lung disease, or hematologic abnormalities. On the contrary, Raynaud's phenomenon, acrosclerosis or peripheral neuropathies are usually resistant to corticosteroids. Cyclophosphamide are useful in interstitial lung disease and in the eventual serious renal involvement. In cases of myositis or thrombocytopenias resistant to corticosteroids, intravenous immunoglobulins may be useful. For Raynaud, general measures (such as tobacco cessation, protection against the cold), calcium antagonists, endovenous prostaglandins or endothelin-2 antagonists may be useful. In patients with gastroesophageal reflux, proton pump inhibitors and H2 receptor antagonists can be used, following protocol for the usual treatment of these scleroderma problems. [24] [25]

Since pulmonary hypertension is the leading cause of death, its early diagnosis by routine echocardiography and the rapid initiation of treatment with endothelin-1 antagonists (bosentan), phosphodiesterase 5 inhibitors (sildenafil) or endovenous prostacyclins (epoprostenol) manage to considerably improve morbidity and mortality. [24] [25]

Investigational

Further investigation into appropriate treatment options for MCTD are in progress.  Treatment for various rheumatoid diseases are currently undergoing research and have the potential to be used for patients presenting with similar signs and symptoms.  Better understanding the pathophysiology of the disease and its progression will enable better targeted treatment options. [12]

Prognosis

The original description of the disease is characterized by a generally good prognosis and an excellent response to treatment with corticosteroids; however, in actuality it is clear that there is a group of patients with elevated morbidity and mortality. In a 2013 study of 280 patients, the survival rates at 5, 10, and 15 years were 98%, 96%, and 88% respectively, with the main causes of death being pulmonary hypertension, cardiovascular problems, and infections. [27] The presence of anticardiolipin antibodies is a more serious risk factor for the disease, as well as the presence of more scleroderma and polymyositis signs and symptoms. [25]

Morbidity is quite high in patients with MCTD. In addition to fatigue and recurrent musculoskeletal complaints, patients can develop a fibromyalgia symptom as a result of occasional outbreaks requiring medium-high doses of corticosteroid.  The steroids, in combination with their adverse effects, frequently cause fibromyalgia symptoms and thus complicate treatment. [25]

The prognosis of mixed connective tissue disease is in one third of cases worse than that of systemic lupus erythematosus (SLE). In spite of prednisone treatment, this disease is progressive and may in many cases evolve into a progressive systemic sclerosis (PSS), also referred to as diffuse cutaneous systemic scleroderma (dcSSc) which has a poor outcome. In some cases though the disease is mild and may only need aspirin as a treatment and may go into remission where no Anti-U1-RNP antibodies are detected, but that is rare or within 30% of cases.[ citation needed ] Most deaths from MCTD are due to heart failure caused by pulmonary arterial hypertension (PAH).

Disease progression

Patients diagnosed with MCTD may progress to a clinical picture more consistent with other connective tissue diseases like SLE, scleroderma, or rheumatoid arthritis. In some studies these patients become reclassified over time with other diseases, such as rheumatoid arthritis in 9%, SLE in 15%, and scleroderma in 21% of cases. [28] Such progression is, in part, determined genetically, thus SLE is more likely in patients with HLA-DR3 and scleroderma in patients with HLA-DR5. [25]

Epidemiology

The prevalence of MCTD is higher than that of dermatomyositis and lower than that of SLE. [29] In a 2011 Norwegian study, the prevalence of MCTD was 3.8 per 100,000 adults, with an incidence of 2.1 per million per year. [30]

MCTD is much more frequent in women than in men at between a 3:1 to 16:1 ratio, and in women younger than 50. [10] The general age at onset is around 15–25 years old.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Systemic scleroderma</span> Medical condition

Systemic scleroderma, or systemic sclerosis, is an autoimmune rheumatic disease characterised by excessive production and accumulation of collagen, called fibrosis, in the skin and internal organs and by injuries to small arteries. There are two major subgroups of systemic sclerosis based on the extent of skin involvement: limited and diffuse. The limited form affects areas below, but not above, the elbows and knees with or without involvement of the face. The diffuse form also affects the skin above the elbows and knees and can also spread to the torso. Visceral organs, including the kidneys, heart, lungs, and gastrointestinal tract can also be affected by the fibrotic process. Prognosis is determined by the form of the disease and the extent of visceral involvement. Patients with limited systemic sclerosis have a better prognosis than those with the diffuse form. Death is most often caused by lung, heart, and kidney involvement. The risk of cancer is increased slightly.

<span class="mw-page-title-main">Antinuclear antibody</span> Autoantibody that binds to contents of the cell nucleus

Antinuclear antibodies are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human proteins (autoantigens). In some cases, antibodies to human antigens are produced.

<span class="mw-page-title-main">Kikuchi disease</span> Medical condition

Kikuchi disease was described in 1972 in Japan. It is also known as histiocytic necrotizing lymphadenitis, Kikuchi necrotizing lymphadenitis, phagocytic necrotizing lymphadenitis, subacute necrotizing lymphadenitis, and necrotizing lymphadenitis. Kikuchi disease occurs sporadically in people with no family history of the condition.

<span class="mw-page-title-main">Raynaud syndrome</span> Medical condition in which spasm of arteries causes episodes of reduced blood flow

Raynaud syndrome, also known as Raynaud's phenomenon, is a medical condition in which the spasm of small arteries causes episodes of reduced blood flow to end arterioles. Typically, the fingers, and less commonly, the toes, are involved. Rarely, the nose, ears, nipples, or lips are affected. The episodes classically result in the affected part turning white and then blue. Often, numbness or pain occurs. As blood flow returns, the area turns red and burns. The episodes typically last minutes but can last several hours. The condition is named after the physician Auguste Gabriel Maurice Raynaud, who first described it in his doctoral thesis in 1862.

<span class="mw-page-title-main">CREST syndrome</span> Medical condition

CREST syndrome, also known as the limited cutaneous form of systemic sclerosis (lcSSc), is a multisystem connective tissue disorder. The acronym "CREST" refers to the five main features: calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia.

An autoantibody is an antibody produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases are associated with such antibodies.

A connective tissue disease is a disease which involves damage to, or destruction of, any type of connective tissue in the body. Depending on the specific disease, the affected tissue(s) may be a single specific type, a group of several related tissues, or a wide variety of unrelated types of connective tissue. Some of the most common connective tissue diseases involve injury to collagen and elastin as a result of inflammation. Many connective tissue diseases are strongly connected to autoimmune disease processes.

Extractable nuclear antigens (ENAs) are over 100 different soluble cytoplasmic and nuclear antigens. They are known as "extractable" because they can be removed from cell nuclei using saline and represent six main proteins: Ro, La, Sm, RNP, Scl-70, Jo1. Most ENAs are part of spliceosomes or nucleosomes complexes and are a type of small nuclear ribonucleoprotein (snRNPS). The location in the nucleus and association with spliceosomes or nucleosomes results in these ENAs being associated with additional RNA and proteins such as polymerases. This quality of ENAs often makes it difficult to purify and quantify their presence for clinical use.

Palindromic rheumatism (PR) is a syndrome characterised by recurrent, self-resolving inflammatory attacks in and around the joints, and consists of arthritis or periarticular soft tissue inflammation. The course is often acute onset, with sudden and rapidly developing attacks or flares. There is pain, redness, swelling, and disability of one or multiple joints. The interval between recurrent palindromic attacks and the length of an attack is extremely variable from few hours to days. Attacks may become more frequent with time but there is no joint damage after attacks. It is thought to be an autoimmune disease, possibly an abortive form of rheumatoid arthritis.

Scleromyositis, is an autoimmune disease. People with scleromyositis have symptoms of both systemic scleroderma and either polymyositis or dermatomyositis, and is therefore considered an overlap syndrome. Although it is a rare disease, it is one of the more common overlap syndromes seen in scleroderma patients, together with MCTD and Antisynthetase syndrome. Autoantibodies often found in these patients are the anti-PM/Scl (anti-exosome) antibodies.

An overlap syndrome is a medical condition which shares features of at least two more widely recognised disorders. Examples of overlap syndromes can be found in many medical specialties such as overlapping connective tissue disorders in rheumatology, and overlapping genetic disorders in cardiology.

<span class="mw-page-title-main">HLA-DR4</span>

HLA-DR4 (DR4) is an HLA-DR serotype that recognizes the DRB1*04 gene products. The DR4 serogroup is large and has a number of moderate frequency alleles spread over large regions of the world.

Anti-topoisomerase antibodies (ATA) are autoantibodies directed against topoisomerase and found in several diseases, most importantly scleroderma. Diseases with ATA are autoimmune disease because they react with self-proteins. They are also referred to as anti-DNA topoisomerase I antibody.

<span class="mw-page-title-main">Lupus erythematosus</span> Human disease

Lupus erythematosus is a collection of autoimmune diseases in which the human immune system becomes hyperactive and attacks healthy tissues. Symptoms of these diseases can affect many different body systems, including joints, skin, kidneys, blood cells, heart, and lungs. The most common and most severe form is systemic lupus erythematosus.

<span class="mw-page-title-main">Anti-dsDNA antibodies</span> Group of anti-nuclear antibodies

Anti-double stranded DNA (Anti-dsDNA) antibodies are a group of anti-nuclear antibodies (ANA) the target antigen of which is double stranded DNA. Blood tests such as enzyme-linked immunosorbent assay (ELISA) and immunofluorescence are routinely performed to detect anti-dsDNA antibodies in diagnostic laboratories. They are highly diagnostic of systemic lupus erythematosus (SLE) and are implicated in the pathogenesis of lupus nephritis.

<span class="mw-page-title-main">Lupus</span> Human autoimmune disease

Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common symptoms include painful and swollen joints, fever, chest pain, hair loss, mouth ulcers, swollen lymph nodes, feeling tired, and a red rash which is most commonly on the face. Often there are periods of illness, called flares, and periods of remission during which there are few symptoms.

Lupus headache is a proposed, specific headache disorder in patients with systemic lupus erythematosus (SLE). Research shows that headache is a symptom commonly described by SLE patients —57% in one meta-analysis, ranging in different studies from 33% to 78%; of which migraine 31.7% and tension-type headache 23.5%. The existence of a special lupus headache is contested, although few high-quality studies are available to form definitive conclusions.

Undifferentiated connective tissue disease (UCTD) is a disease in which the connective tissues are targeted by the immune system. It is a serological and clinical manifestation of an autoimmune disease. When there is proof of an autoimmune disease, it will be diagnosed as UCTD if the disease doesn't answer to any criterion of specific autoimmune disease. This is also the case of major rheumatic diseases whose early phase was defined by LeRoy et al. in 1980 as undifferentiated connective tissue disease.

<span class="mw-page-title-main">Anti-SSA/Ro autoantibodies</span> Type of anti-nuclear autoantibodies

Anti-SSA autoantibodies are a type of anti-nuclear autoantibodies that are associated with many autoimmune diseases, such as systemic lupus erythematosus (SLE), SS/SLE overlap syndrome, subacute cutaneous lupus erythematosus (SCLE), neonatal lupus and primary biliary cirrhosis. They are often present in Sjögren's syndrome (SS). Additionally, Anti-Ro/SSA can be found in other autoimmune diseases such as systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), rheumatoid arthritis (RA), and mixed connective tissue disease (MCTD), and are also associated with heart arrhythmia.

<span class="mw-page-title-main">Lupus vasculitis</span> Medical condition

Lupus vasculitis is one of the secondary vasculitides that occurs in approximately 50% of patients with systemic lupus erythematosus (SLE).

References

  1. 1 2 Rapini RP, Bolognia JL, Jorizzo JL (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN   978-1-4160-2999-1.
  2. 1 2 3 Bennett, Robert (2014). "Clinical manifestations of mixed connective tissue disease". www.uptodate.com. Retrieved 2019-10-12.
  3. 1 2 3 Ungprasert, Patompong; Crowson, Cynthia S.; Chowdhary, Vaidehi R.; Ernste, Floranne C.; Moder, Kevin G.; Matteson, Eric L. (December 2016). "Epidemiology of Mixed Connective Tissue Disease 1985-2014: A Population Based Study". Arthritis Care & Research. 68 (12): 1843–1848. doi:10.1002/acr.22872. ISSN   2151-464X. PMC   5426802 . PMID   26946215.
  4. 1 2 Sharp GC, Irvin WS, Tan EM, Gould RG, Holman HR (February 1972). "Mixed connective tissue disease--an apparently distinct rheumatic disease syndrome associated with a specific antibody to an extractable nuclear antigen (ENA)". The American Journal of Medicine. 52 (2): 148–59. doi:10.1016/0002-9343(72)90064-2. PMID   4621694.
  5. Tsokos GC, Gordon C, Smolen JS (2007). Systemic lupus erythematosus: a companion to Rheumatology. Elsevier Health Sciences. pp. 429–. ISBN   978-0-323-04434-9.
  6. LeRoy EC, Maricq HR, Kahaleh MB (March 1980). "Undifferentiated connective tissue syndromes". Arthritis and Rheumatism. 23 (3): 341–3. doi: 10.1002/art.1780230312 . PMID   7362686.
  7. 1 2 Hoffman RW (1 June 2009). "Mixed Connective Disease". In Stone J (ed.). Pearls & Myths in Rheumatology. Springer. pp. 169–172. ISBN   978-1-84800-933-2 . Retrieved 26 June 2010.
  8. "Mixed Connective Tissue Disease, MCTD". The Free Dictionary by Farlex.
  9. Nevares AM, Larner R. "Mixed Connective Tissue Disease (MCTD): Autoimmune Disorders of Connective Tissue". Merck Manual Home Health Handbook.
  10. 1 2 "Mixed connective tissue disease - Symptoms and causes". Mayo Clinic. Retrieved 2019-10-12.
  11. Yang, Chia-Fu; Chiu, Jih-Yu; Su, Chang-Wei; Chen, Chun-Ming (2019). "Chondral grafts for condylar reconstruction in treatment of temporomandibular joint arthritis in a mixed connective tissue disease patient". The Kaohsiung Journal of Medical Sciences. 35 (12): 787–788. doi: 10.1002/kjm2.12128 . ISSN   2410-8650. PMID   31512336.
  12. 1 2 "Mixed Connective Tissue Disease (MCTD)". NORD (National Organization for Rare Disorders). Retrieved 2019-10-12.
  13. Aringer M, Steiner G, Smolen JS (August 2005). "Does mixed connective tissue disease exist? Yes". Rheumatic Disease Clinics of North America. 31 (3): 411–20, v. doi:10.1016/j.rdc.2005.04.007. PMID   16084315.
  14. Venables PJ (2006). "Mixed connective tissue disease". Lupus. 15 (3): 132–7. doi:10.1191/0961203306lu2283rr. PMID   16634365. S2CID   25736411.
  15. Sato T, Fujii T, Yokoyama T, Fujita Y, Imura Y, Yukawa N, Kawabata D, Nojima T, Ohmura K, Usui T, Mimori T (December 2010). "Anti-U1 RNP antibodies in cerebrospinal fluid are associated with central neuropsychiatric manifestations in systemic lupus erythematosus and mixed connective tissue disease". Arthritis and Rheumatism. 62 (12): 3730–40. doi:10.1002/art.27700. hdl: 2433/142082 . PMID   20722023.
  16. Cappelli, Susanna; Bellando Randone, Silvia; Martinović, Dušanka; Tamas, Maria-Magdalena; Pasalić, Katarina; Allanore, Yannick; Mosca, Marta; Talarico, Rosaria; Opris, Daniela; Kiss, Csaba G.; Tausche, Anne-Kathrin (February 2012). ""To be or not to be," ten years after: evidence for mixed connective tissue disease as a distinct entity". Seminars in Arthritis and Rheumatism. 41 (4): 589–598. doi:10.1016/j.semarthrit.2011.07.010. ISSN   1532-866X. PMID   21959290.
  17. Alarcón-Segovia, D.; Cardiel, M. H. (March 1989). "Comparison between 3 diagnostic criteria for mixed connective tissue disease. Study of 593 patients". The Journal of Rheumatology. 16 (3): 328–334. ISSN   0315-162X. PMID   2724251.
  18. "Sociedad Española de Reumatología :: Criterios diagnósticos". 2014-08-10. Archived from the original on 2014-08-10. Retrieved 2019-10-12.
  19. 1 2 3 Bennett, Robert. "Definition and diagnosis of mixed connective tissue disease". Archived from the original on 2020-08-15. Retrieved 2019-10-12.
  20. Alves, Marta (2020). ""Mixed connective tissue disease": a condition in search of an identity". Clinical and Experimental Medicine. 20 (2): 159–166. doi:10.1007/s10238-020-00606-7. PMC   7181542 . PMID   32130548.
  21. Greidinger, Eric L.; Hoffman, Robert W. (August 2005). "Autoantibodies in the pathogenesis of mixed connective tissue disease". Rheumatic Disease Clinics of North America. 31 (3): 437–450, vi. doi:10.1016/j.rdc.2005.04.004. ISSN   0889-857X. PMID   16084317.
  22. Gendi, N. S.; Welsh, K. I.; Van Venrooij, W. J.; Vancheeswaran, R.; Gilroy, J.; Black, C. M. (February 1995). "HLA type as a predictor of mixed connective tissue disease differentiation. Ten-year clinical and immunogenetic followup of 46 patients". Arthritis and Rheumatism. 38 (2): 259–266. doi:10.1002/art.1780380216. ISSN   0004-3591. PMID   7848317.
  23. "Table 1: The Single Nucleotide Polymorphisms in cathepsin B protein mined from literature (PMID: 16492714)". doi: 10.7717/peerj.7425/table-1 .{{cite journal}}: Cite journal requires |journal= (help)
  24. 1 2 3 Mobasat, A.; Turrión Nieves, A.; Bohorquez Heras, C. (January 2013). "Enfermedad mixta del tejido conectivo. Síndromes de solapamiento". Medicine - Programa de Formación Médica Continuada Acreditado. 11 (32): 1991–1996. doi:10.1016/s0304-5412(13)70567-5. ISSN   0304-5412.
  25. 1 2 3 4 5 6 Bennett, Robert. "Prognosis and treatment of mixed connective tissue disease".
  26. Yang, Chia-Fu; Chiu, Jih-Yu; Su, Chang-Wei; Chen, Chun-Ming (2019-09-11). "Chondral grafts for condylar reconstruction in treatment of temporomandibular joint arthritis in a mixed connective tissue disease patient". The Kaohsiung Journal of Medical Sciences. 35 (12): 787–788. doi: 10.1002/kjm2.12128 . ISSN   1607-551X. PMID   31512336.
  27. Hajas, Agota; Szodoray, Peter; Nakken, Britt; Gaal, Janos; Zöld, Eva; Laczik, Renata; Demeter, Nora; Nagy, Gabor; Szekanecz, Zoltan; Zeher, Margit; Szegedi, Gyula (July 2013). "Clinical course, prognosis, and causes of death in mixed connective tissue disease". The Journal of Rheumatology. 40 (7): 1134–1142. doi: 10.3899/jrheum.121272 . ISSN   0315-162X. PMID   23637328. S2CID   19625256.
  28. Ruiz Pombo, Mónica; Labrador Horrillo, Moisés; Selva O'Callaghan, Albert (2004-11-20). "[Undifferentiated, overlapping and mixed connective tissue diseases]". Medicina Clinica. 123 (18): 712–717. doi:10.1016/s0025-7753(04)75337-3. ISSN   0025-7753. PMID   15563821.
  29. "Mixed Connective-Tissue Disease: Practice Essentials, Pathophysiology, Etiology". 2019-07-17.{{cite journal}}: Cite journal requires |journal= (help)
  30. Gunnarsson, Ragnar; Molberg, Oyvind; Gilboe, Inge-Margrethe; Gran, Jan Tore; PAHNOR1 Study Group (June 2011). "The prevalence and incidence of mixed connective tissue disease: a national multicentre survey of Norwegian patients". Annals of the Rheumatic Diseases. 70 (6): 1047–1051. doi:10.1136/ard.2010.143792. hdl: 10852/36041 . ISSN   1468-2060. PMID   21398332. S2CID   206864939.{{cite journal}}: CS1 maint: numeric names: authors list (link)

Further reading