Adenosine deaminase 2 deficiency

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Deficiency of Adenosine deaminase 2 (DADA2) is a monogenic disease associated with systemic inflammation and vasculopathy that affects a wide variety of organs in different patients. As a result, it is hard to characterize a patient with this disorder. Manifestations of the disease include but are not limited to recurrent fever, livedoid rash (reticularis or racemosa), various cytopenias, stroke, immunodeficiency, and bone marrow failure.[1][2] Symptoms often onset during early childhood, but some cases have been discovered as late as 65 years old.[3]

Deficiency of Adenosine Deaminase 2
Other namesDADA2
Autosomal recessive pattern is the inheritance manner of this condition
SpecialtyMedical genetics, Pediatrics, Rheumatology, Neurology, Dermatology, Immunology, Hematology
Usual onsetVariable, but commonly in early childhood
DurationLifelong
CausesMutations in the ADA2 gene
Diagnostic methodGenetic or Enzymatic Testing

DADA2 is caused by mutations in the ADA2 gene, and is inherited in an autosomal recessive manner. The protein product of this gene, adenosine deaminase 2 (ADA2), is an extracellular enzyme that breaks down adenosine and may also serve as a growth factor. Pathogenic mutations decrease this enzymatic activity in patient blood, leading to disease manifestations. However, mutational status and residual enzyme activity levels do not explicitly correlate with the type of disease a patient displays.[4][2][1]

The most common treatment for DADA2 is TNF inhibitors. This therapy tends to prevent vasculitis-related manifestations such as rash and stroke,[5][6] but does not perform well in individuals presenting with severe hematologic and immunologic abnormalities such as bone marrow failure or severe recurrent infections.[7] In these cases, hematopoietic stem cell transplantation has led to major improvements in the vascular, hematologic, and immunologic manifestations of disease.[8]

Signs and symptoms

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The signs and symptoms of disease are wide-ranging in severity, but can be grouped into vascular, immunologic, and hematologic manifestations. Individual patients typically present with disease of only one of these subtypes, but this is not always the case.  Symptoms have also been known to abate and recur even without treatment.[9] Twenty-four percent of patients have disease onset before 1 year of age, and 77% of patients have disease onset before 10 years of age.[2]

Vasculopathy is the hallmark of DADA2, and was the most prominent feature of the disease upon its initial discovery.[10][11] The vasculitis seen in DADA2 is similar to polyarteritis nodosa (PAN), often leading to misdiagnosis. However, DADA2 patients typically have earlier disease onset, and a greater prevalence of skin and neurologic manifestations.[12] The systemic inflammation present in DADA2 leads to this vasculopathy, with symptoms involving but not limited to skin, brain, gastrointestinal tract, and kidneys. Livedo racemosa and livedo reticularis are the most common manifestations in skin, although other symptoms such as digital necrosis, subcutaneous nodules, and non-specific rash have been seen.  The most common neurological manifestations of DADA2 are secondary to vasculitis.  Fifty-one percent of patients present with neurologic disease, typically in the form of lacunar stroke.[2] In some patients, stroke can be the first indication of disease.[13]

Approximately 50% of patients have some form of immunologic or hematologic disease.[2]  While patients with vascular-predominant disease typically have only mild deficiencies in these areas,[4] most DADA2 patients display deficiencies in IgG and IgM antibody production as well as overall poor B cell function.[14]  Bone marrow failure, pure red cell aplasia (PRCA), or immunodeficiency are the most serious manifestations in those who don't display the classic vascular disease.  Those with the bone marrow failure phenotype commonly have hepatosplenomegaly, recurrent infection, and various cytopenias.  Meanwhile, those with PRCA can display a similar disease to Diamond-Blackfan anemia.[15] The onset of PRCA caused by DADA2 is commonly before one year of age, while children with bone marrow failure typically onset around two years of age.[4]  In patients with severe immunodeficiencies, upper and lower respiratory infections are most common. However, intestinal and urinary tract infections have been seen alongside various more rare infections such as viral encephalitis.[14]

There are a variety of rare DADA2 symptoms that have only been reported in a handful of patients.  For example, lymphoproliferation and large granular lymphocytic leukemia have been reported.[16][17][18] Other symptoms are becoming more known over time – reports of hypertension associated with DADA2 have increased in recent years.[19][20][21]

Genetics

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DADA2 is caused by mutations in DNA encoding the gene ADA2, formerly known as CECR1. The ADA2 gene is located on chromosome 22q11.1.[22]  Many different kinds of mutations have been reported, including missense, nonsense, splice-site, frameshift, deletions, and duplications. As of 2021, there are 117 known mutations, although classification into disease-causing and benign is ongoing.[23]

While there is some relationship between the genetic mutations a patient displays and their experience with the disease, the relationship is not one to one. Patients with DADA2 that share the same mutation are more likely to experience similar disease, but even family members with the same mutations have had entirely different disease courses.[4][24][25] While the reasons for this difference are not well defined in DADA2 this is common in other so-called monogenic diseases, where environment and modifier genetics have been shown to play a role.[26][27][28][29] However, multiple groups have found some correlation between mutation and phenotype. There is some indication that mutations present in the dimerization domain of ADA2 predispose towards vasculitis-associated disease, whereas mutations in the catalytic domain lead to the Diamond Blackfan anemia-like phenotype.[30] In another study, specific mutations segregated perfectly into groups based on the type of the disease the patient displayed. In this analysis, the common G47R mutation always found in individuals with vasculitic disease, and the G358R mutation always seen in those with severe hematologic disease. However, some mutations did not separate as well. For example, the R169Q mutation was found in both vasculitic- and hematologic-forward disease subtypes.[4]  An analysis of the enzymatic activity of mutated ADA2 enzyme in vitro found that mutations yielding greater enzyme activity favored vasculitis, whereas mutations with less residual activity favored hematologic manifestations.[4]

Pathophysiology

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The mechanism by which mutations in ADA2 lead to disease manifestations is not fully clear.  ADA2 is a primarily extracellular protein highly expressed by myeloid immune cells such as monocytes, macrophages, and dendritic cells.[31][32] ADA2 has been hypothesized to have multiple functions, including as an enzyme, a growth factor, and an intracellular DNA sensor.[33][2]

ADA2 catalyzes the reaction of adenosine to inosine and 2'deoxyadenosine in the blood.  All DADA2 patients display less than 5% of the normal activity of ADA2 in blood samples, implicating the potential importance of this enzymatic role.[4]  Adenosine levels are higher in patients than healthy individuals.[34] Adenosine binds to cell surface receptors on neutrophils, causing the formation of neutrophil extracellular traps (NETs).  NETs have been identified at increased levels in both affected tissue and in circulation of DADA2 patients.[34]

Endothelial cell activation and damage is a further source of inflammation and vascular symptoms caused by DADA2. Endothelial cells from patients are extensively damaged and secrete pro-inflammatory cytokines. However, endothelial cells themselves don't express the ADA2 protein, so this phenotype is likely mediated by the effects of mutant ADA2 on other cell types feeding back onto endothelial cells. For example, ADA2 mutant monocytes display abnormal differentiation into macrophages, and endothelial cells grown in the presence of ADA2 deficient monocytes are similarly extensively damaged.[11]  

The molecular underpinnings of the immunologic disease are unclear, but the upregulation of type I interferon-stimulated genes, poor B cell differentiation, reduced antibody production, and lymphoproliferation have been noted.[2] The cause of severe hematologic manifestations such as pure red cell aplasia and bone marrow failure are also unknown.[2] However,  the ADA2 protein is similar in structure to the adenosine deaminase growth factors found in other species.  Deficiencies of these proteins in frogs and fruit flies have been shown to cause developmental abnormalities, such as small size and early death respectively.[35][36][37] In humans, extracellular ADA2 interacts with many immune cell types, including neutrophils, monocytes, NK cells, and specific B and T cell subtypes.[38]

Diagnosis

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Currently, screening for DADA2 is initiated upon a physician's judgement. Criteria to trigger screening have been proposed however, including at least one sign of inflammation and vasculitis.[39] The specific diagnosis of DADA2 requires either confirmation of known pathogenic mutations in ADA2 or low ADA2 enzymatic activity in patient blood.[40]  Genetic testing for DADA2 has been performed as either a single-gene test through Sanger sequencing, or a multi-gene test through panel testing, whole exome sequencing, or whole genome sequencing.[40] These techniques vary in cost, intensity, and detection, and mutations have been missed due to the technique initially used.[41][42] As such, more extensive analysis is sometimes necessary if suspicion of DADA2 remains. Enzymatic activity analysis can confirm whether or not the ADA2 gene should be investigated further in these situations, and has been recommended by some as the premier diagnostic technique.[43]

Management

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The most common management of DADA2 after diagnosis is TNFa inhibition (TNFi). This treatment serves those with vasculitic forms of the disease best, improving most symptoms and significantly preventing strokes.[5][6] TNFi is ineffective in those with severe bone marrow dysfunction or immunodeficiency.[44]  In these patients, hematopoietic stem cell transplant is considered and upon successful completion can be curative.[44][8]

Ongoing pre-clinical studies are researching gene therapy.[45][46] Both gene therapy and enzyme replacement therapy have been successful in the adenosine deaminase deficiency,[47][48] indicating their potential future success in DADA2.

Epidemiology

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As of 2020, over 260 cases of DADA2 have been identified since the disease's discovery in 2014.[40] Since this disease is inherited in an autosomal recessive manner, men and women are equally likely to be diagnosed with DADA2. Based on computational analyses, the prevalence of DADA2 could be as high as 4 in 100,000.[49]  Generally, populations with high degrees of consanguinity or with founder variants have a higher prevalence of DADA2. For example, the Georgian-Jewish and Turkish populations are estimated to have a 1:10 and 1:500 likelihood of carrying the G47R mutation respectively.  The R169Q variant is also more common in northern Europe, with a carrier frequency of 1:500.[49]

History

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DADA2 was discovered in 2014 by two independent groups at the NIH and in Jerusalem, each reporting systemic inflammation and vasculitis syndromes caused by mutations in ADA2.[10][11] The DADA2 Foundation was formed in 2016 to serve patients with DADA2 by providing information and spurring research progress. The Foundation has organized an international DADA2 Conference, being held in 2016, 2018, 2020 and 2023.[50]

References

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  1. ^ a b Lee PY (2018). "Vasculopathy, Immunodeficiency, and Bone Marrow Failure: The Intriguing Syndrome Caused by Deficiency of Adenosine Deaminase 2". Frontiers in Pediatrics. 6: 282. doi:10.3389/fped.2018.00282. PMC 6200955. PMID 30406060.
  2. ^ a b c d e f g h Meyts I, Aksentijevich I (July 2018). "Deficiency of Adenosine Deaminase 2 (DADA2): Updates on the Phenotype, Genetics, Pathogenesis, and Treatment". Journal of Clinical Immunology. 38 (5): 569–578. doi:10.1007/s10875-018-0525-8. PMC 6061100. PMID 29951947.
  3. ^ Bourgeois G, Richard M, Danset M, Pérard L, Breton AL, Berthoux E (March 2021). "Deficiency of adenosine deaminase 2 diagnosed at 65 years of age". Lancet. 397 (10277): 913. doi:10.1016/S0140-6736(20)32660-X. PMID 33676630. S2CID 232116912.
  4. ^ a b c d e f g Lee PY, Kellner ES, Huang Y, Furutani E, Huang Z, Bainter W, et al. (June 2020). "Genotype and functional correlates of disease phenotype in deficiency of adenosine deaminase 2 (DADA2)". The Journal of Allergy and Clinical Immunology. 145 (6): 1664–1672.e10. doi:10.1016/j.jaci.2019.12.908. PMC 7282972. PMID 31945408.
  5. ^ a b Ombrello AK, Qin J, Hoffmann PM, Kumar P, Stone D, Jones A, et al. (April 2019). "Treatment Strategies for Deficiency of Adenosine Deaminase 2". The New England Journal of Medicine. 380 (16): 1582–1584. doi:10.1056/NEJMc1801927. PMC 7372950. PMID 30995379.
  6. ^ a b Sharma A, Naidu G, Sharma V, Jha S, Dhooria A, Dhir V, et al. (February 2021). "Deficiency of Adenosine Deaminase 2 in Adults and Children: Experience From India". Arthritis & Rheumatology. 73 (2): 276–285. doi:10.1002/art.41500. PMC 7902299. PMID 32892503.
  7. ^ Conticini E, Sota J, Falsetti P, Lamberti A, Miracco C, Guarnieri A, et al. (April 2021). "Biologic drugs in the treatment of polyarteritis nodosa and deficit of adenosine deaminase 2: A narrative review". Autoimmunity Reviews. 20 (4): 102784. doi:10.1016/j.autrev.2021.102784. PMID 33609794. S2CID 231979636.
  8. ^ a b Hashem H, Kumar AR, Müller I, Babor F, Bredius R, Dalal J, et al. (December 2017). "Hematopoietic stem cell transplantation rescues the hematological, immunological, and vascular phenotype in DADA2". Blood. 130 (24): 2682–2688. doi:10.1182/blood-2017-07-798660. PMC 5731089. PMID 28974505.
  9. ^ Betrains A, Staels F, Moens L, Delafontaine S, Hershfield MS, Blockmans D, et al. (February 2021). "Diagnosis of deficiency of adenosine deaminase type 2 in adulthood" (PDF). Scandinavian Journal of Rheumatology. 50 (6): 493–496. doi:10.1080/03009742.2021.1881156. PMID 33627040. S2CID 232048348.
  10. ^ a b Navon Elkan P, Pierce SB, Segel R, Walsh T, Barash J, Padeh S, et al. (March 2014). "Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy". The New England Journal of Medicine. 370 (10): 921–31. doi:10.1056/NEJMoa1307362. PMID 24552285.
  11. ^ a b c Zhou Q, Yang D, Ombrello AK, Zavialov AV, Toro C, Zavialov AV, et al. (March 2014). "Early-onset stroke and vasculopathy associated with mutations in ADA2". The New England Journal of Medicine. 370 (10): 911–20. doi:10.1056/NEJMoa1307361. PMC 4193683. PMID 24552284.
  12. ^ Caorsi R, Penco F, Grossi A, Insalaco A, Omenetti A, Alessio M, et al. (October 2017). "ADA2 deficiency (DADA2) as an unrecognised cause of early onset polyarteritis nodosa and stroke: a multicentre national study". Annals of the Rheumatic Diseases. 76 (10): 1648–1656. doi:10.1136/annrheumdis-2016-210802. hdl:11368/2964583. PMID 28522451. S2CID 39815969.
  13. ^ Elbracht M, Mull M, Wagner N, Kuhl C, Abicht A, Kurth I, et al. (April 2017). "Stroke as Initial Manifestation of Adenosine Deaminase 2 Deficiency". Neuropediatrics. 48 (2): 111–114. doi:10.1055/s-0036-1597611. PMID 28024309. S2CID 37168653.
  14. ^ a b Schepp J, Proietti M, Frede N, Buchta M, Hübscher K, Rojas Restrepo J, et al. (August 2017). "Screening of 181 Patients With Antibody Deficiency for Deficiency of Adenosine Deaminase 2 Sheds New Light on the Disease in Adulthood". Arthritis & Rheumatology. 69 (8): 1689–1700. doi:10.1002/art.40147. PMID 28493328. S2CID 205433642.
  15. ^ Sasa G (2015). "Adenosine Deaminase 2 Deficiency As a Cause of Pure Red Cell Aplasia Mimicking Diamond Blackfan Anemia". Blood. 126 (23): 3615. doi:10.1182/blood.V126.23.3615.3615 – via ASH Publications.
  16. ^ Trotta L, Martelius T, Siitonen T, Hautala T, Hämäläinen S, Juntti H, et al. (April 2018). "ADA2 deficiency: Clonal lymphoproliferation in a subset of patients". The Journal of Allergy and Clinical Immunology. 141 (4): 1534–1537.e8. doi:10.1016/j.jaci.2018.01.012. PMID 29391253.
  17. ^ Alsultan A, Basher E, Alqanatish J, Mohammed R, Alfadhel M (April 2018). "Deficiency of ADA2 mimicking autoimmune lymphoproliferative syndrome in the absence of livedo reticularis and vasculitis". Pediatric Blood & Cancer. 65 (4): e26912. doi:10.1002/pbc.26912. PMID 29271561. S2CID 3441818.
  18. ^ Saettini F, Fazio G, Corti P, Quadri M, Bugarin C, Gaipa G, et al. (September 2020). "Two siblings presenting with novel ADA2 variants, lymphoproliferation, persistence of large granular lymphocytes, and T-cell perturbations". Clinical Immunology. 218: 108525. doi:10.1016/j.clim.2020.108525. PMID 32659374. S2CID 220521603.
  19. ^ Springer JM, Gierer SA, Jiang H, Kleiner D, Deuitch N, Ombrello AK, et al. (2018-06-14). "Deficiency of Adenosine Deaminase 2 in Adult Siblings: Many Years of a Misdiagnosed Disease With Severe Consequences". Frontiers in Immunology. 9: 1361. doi:10.3389/fimmu.2018.01361. PMC 6010516. PMID 29963054.
  20. ^ Ouail DE, Tebbani M, Ahmed DS, Bouali F (July 2019). "Youth Hypertension Associated With ada2 Deficiency. About Three Cases". Journal of Hypertension. 37: e215. doi:10.1097/01.hjh.0000572764.95461.72.
  21. ^ Sahin S, Adrovic A, Barut K, Baran S, Tahir Turanli E, Canpolat N, et al. (February 2020). "A 9.5-year-old boy with recurrent neurological manifestations and severe hypertension, treated initially for polyarteritis nodosa, was subsequently diagnosed with adenosine deaminase type 2 deficiency (DADA2) which responded to anti-TNF-α". Paediatrics and International Child Health. 40 (1): 65–68. doi:10.1080/20469047.2018.1559495. PMID 30642227. S2CID 58576432.
  22. ^ "ADA2 Gene — GeneCards | ADA2 Protein | ADA2 Antibody". www.genecards.org. Retrieved 2021-04-12.
  23. ^ Aksentijevich I. "ADA2 Sequence Variants". infevers.umai-montpellier.fr. Archived from the original on 2020-09-27. Retrieved 2021-04-12.
  24. ^ Schnappauf O, Zhou Q, Moura NS, Ombrello AK, Michael DG, Deuitch N, et al. (August 2020). "Deficiency of Adenosine Deaminase 2 (DADA2): Hidden Variants, Reduced Penetrance, and Unusual Inheritance". Journal of Clinical Immunology. 40 (6): 917–926. doi:10.1007/s10875-020-00817-3. PMC 7416912. PMID 32638197.
  25. ^ Neishabury M, Mehri M, Fattahi Z, Najmabadi H, Azarkeivan A (January 2020). "Novel variants in Iranian individuals suspected to have inherited red blood cell disorders, including bone marrow failure syndromes". Haematologica. 105 (1): e1–e4. doi:10.3324/haematol.2019.216069. PMC 6939539. PMID 31097629.
  26. ^ Weatherall DJ (April 2001). "Phenotype-genotype relationships in monogenic disease: lessons from the thalassaemias". Nature Reviews. Genetics. 2 (4): 245–55. doi:10.1038/35066048. PMID 11283697. S2CID 205014931.
  27. ^ Scriver CR, Waters PJ (July 1999). "Monogenic traits are not simple: lessons from phenylketonuria". Trends in Genetics. 15 (7): 267–272. doi:10.1016/S0168-9525(99)01761-8. PMID 10390625.
  28. ^ Gallati S (July 2014). "Disease-modifying genes and monogenic disorders: experience in cystic fibrosis". The Application of Clinical Genetics. 7: 133–46. doi:10.2147/TACG.S18675. PMC 4104546. PMID 25053892.
  29. ^ Davidson BA, Hassan S, Garcia EJ, Tayebi N, Sidransky E (December 2018). "Exploring genetic modifiers of Gaucher disease: The next horizon". Human Mutation. 39 (12): 1739–1751. doi:10.1002/humu.23611. PMC 6240360. PMID 30098107.
  30. ^ Özen S, Batu ED, Taşkıran EZ, Özkara HA, Ünal Ş, Güleray N, et al. (January 2020). "A Monogenic Disease with a Variety of Phenotypes: Deficiency of Adenosine Deaminase 2". The Journal of Rheumatology. 47 (1): 117–125. doi:10.3899/jrheum.181384. PMID 31043544. S2CID 143423444.
  31. ^ Zavialov AV, Gracia E, Glaichenhaus N, Franco R, Zavialov AV, Lauvau G (August 2010). "Human adenosine deaminase 2 induces differentiation of monocytes into macrophages and stimulates proliferation of T helper cells and macrophages". Journal of Leukocyte Biology. 88 (2): 279–90. doi:10.1189/jlb.1109764. PMID 20453107.
  32. ^ Iwaki-Egawa S, Yamamoto T, Watanabe Y (March 2006). "Human plasma adenosine deaminase 2 is secreted by activated monocytes". Biological Chemistry. 387 (3): 319–21. doi:10.1515/BC.2006.042. PMID 16542154. S2CID 34740291.
  33. ^ Greiner-Tollersrud OK, Krausz M, Bartok E, Boehler V, Ebersbach H, Baash S, et al. (2020-06-22). "ADA2 is a lysosomal DNase regulating the type-I interferon response". bioRxiv: 2020.06.21.162990. doi:10.1101/2020.06.21.162990. S2CID 220044343.
  34. ^ a b Carmona-Rivera C (2019). "Deficiency of adenosine deaminase triggers adenosine-mediated NETosis and TNF production in patients with DADA2". Blood. 134 (4): 395–406. doi:10.1182/blood.2018892752. PMC 6659253. PMID 31015188.
  35. ^ Iijima R, Kunieda T, Yamaguchi S, Kamigaki H, Fujii-Taira I, Sekimizu K, et al. (January 2008). "The extracellular adenosine deaminase growth factor, ADGF/CECR1, plays a role in Xenopus embryogenesis via the adenosine/P1 receptor". The Journal of Biological Chemistry. 283 (4): 2255–64. doi:10.1074/jbc.M709279200. PMID 18032387.
  36. ^ Dolezal T, Dolezelova E, Zurovec M, Bryant PJ (July 2005). "A role for adenosine deaminase in Drosophila larval development". PLOS Biology. 3 (7): e201. doi:10.1371/journal.pbio.0030201. PMC 1135298. PMID 15907156.
  37. ^ Dolezelova E, Zurovec M, Dolezal T, Simek P, Bryant PJ (May 2005). "The emerging role of adenosine deaminases in insects". Insect Biochemistry and Molecular Biology. 35 (5): 381–9. doi:10.1016/j.ibmb.2004.12.009. PMID 15804573.
  38. ^ Kaljas Y, Liu C, Skaldin M, Wu C, Zhou Q, Lu Y, et al. (February 2017). "Human adenosine deaminases ADA1 and ADA2 bind to different subsets of immune cells". Cellular and Molecular Life Sciences. 74 (3): 555–570. doi:10.1007/s00018-016-2357-0. PMC 11107696. PMID 27663683. S2CID 23033160.
  39. ^ Rama M, Duflos C, Melki I, Bessis D, Bonhomme A, Martin H, et al. (July 2018). "A decision tree for the genetic diagnosis of deficiency of adenosine deaminase 2 (DADA2): a French reference centres experience". European Journal of Human Genetics. 26 (7): 960–971. doi:10.1038/s41431-018-0130-6. PMC 6018671. PMID 29681619.
  40. ^ a b c Kendall JL, Springer JM (August 2020). "The Many Faces of a Monogenic Autoinflammatory Disease: Adenosine Deaminase 2 Deficiency". Current Rheumatology Reports. 22 (10): 64. doi:10.1007/s11926-020-00944-1. PMC 7448703. PMID 32845415.
  41. ^ Vairo FP, Koster MJ, Kemppainen JL, Thomas BC, Warrington KJ (January 2021). "Comment on: Anti-tumour necrosis factor treatment for the prevention of ischaemic events in patients with deficiency of adenosine deaminase 2 (DADA2)". Rheumatology. 60 (keab081): e218–e219. doi:10.1093/rheumatology/keab081. PMID 33515254.
  42. ^ Claassen D, Boals M, Bowling KM, Cooper GM, Cox J, Hershfield M, et al. (December 2018). "Complexities of genetic diagnosis illustrated by an atypical case of congenital hypoplastic anemia". Cold Spring Harbor Molecular Case Studies. 4 (6): a003384. doi:10.1101/mcs.a003384. PMC 6318771. PMID 30559313.
  43. ^ Moura N (2019-05-16). "10th Congress of International Society of Systemic Auto-Inflammatory Diseases (ISSAID)". Pediatric Rheumatology Online Journal. 17 (Suppl 1): 18. doi:10.1186/s12969-019-0313-x. PMC 7103907.
  44. ^ a b Cooray S, Omyinmi E, Hong Y, Papadopoulou C, Harper L, Al-Abadi E, et al. (January 2021). "Anti-tumour necrosis factor treatment for the prevention of ischaemic events in patients with deficiency of adenosine deaminase 2 (DADA2)". Rheumatology. 60 (keaa837): 4373–4378. doi:10.1093/rheumatology/keaa837. PMID 33420503.
  45. ^ Brigida I (2019-05-16). "10th Congress of International Society of Systemic Auto-Inflammatory Diseases (ISSAID)". Pediatric Rheumatology Online Journal. 17 (Suppl 1): 18. doi:10.1186/s12969-019-0313-x. ISSN 1546-0096. PMC 7103907.
  46. ^ Hong Y (2019-05-16). "10th Congress of International Society of Systemic Auto-Inflammatory Diseases (ISSAID)". Pediatric Rheumatology Online Journal. 17 (Suppl 1): 18. doi:10.1186/s12969-019-0313-x. ISSN 1546-0096. PMC 7103907.
  47. ^ Hershfield, Michael S. (1995-09-01). "PEG-ADA replacement therapy for adenosine deaminase deficiency: an update after 8.5 years". Clinical Immunology and Immunopathology. 76 (3): S228–S232. doi:10.1016/S0090-1229(95)90306-2. ISSN 0090-1229. PMID 7554473.
  48. ^ Aiuti A, Roncarolo MG, Naldini L (June 2017). "Gene therapy for ADA-SCID, the first marketing approval of an exvivo gene therapy in Europe: paving the road for the next generation of advanced therapy medicinal products". EMBO Molecular Medicine. 9 (6): 737–740. doi:10.15252/emmm.201707573. PMC 5452047. PMID 28396566.
  49. ^ a b Aksentijevich I (1993). "Adenosine Deaminase 2 Deficiency". In Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJ, Mirzaa G, Amemiya A (eds.). GeneReviews. University of Washington, Seattle. PMID 31393689.
  50. ^ "DADA2 Foundation — Supporting research into ADA2 deficiency". DADA2 Foundation. Retrieved 2021-04-12.