|Year : 2019 | Volume
| Issue : 3 | Page : 236-240
Adenosine deaminase 2 deficiency with a novel variant of CECR1 gene mutation: Responding to tumor necrosis factor antagonist therapy
Zakiya Saleh Al Mosawi1, Hiba Omar Abduljawad2, Maryam Yusuf Busehail3, Barrak Mahmood Al Moosawi1
1 Department of Pediatric, Salmaniya Medical Center, Manama, Kingdom of Bahrain
2 Department of Radiology, King Hamad university Hospital, Kingdom of Bahrain
3 Genetic Unit, Salmaniya Medical Complex, Manama, Bahrain, Kingdom of Bahrain
|Date of Web Publication||30-Oct-2019|
Dr. Zakiya Saleh Al Mosawi
Pediatric Rheumatologist, Consultant, Department of Pediatric, Salmaniya Medical Center, PO Box: 12, Manama
Kingdom of Bahrain
Source of Support: None, Conflict of Interest: None
Deficiency of Adenosine deaminase 2 (DADA2) syndrome is a chronic, systemic, and inflammatory disorder, characterized by early-onset recurrent strokes, fever, livedo reticularis, and immunodeficiency. We report the case of a 4-year-old child, a product of consanguineous marriage, who presented with three episodes of hemiparesis within 1 year. She also manifested skin discoloration in the form of livedo reticularis. Workup with magnetic resonance imaging (MRI) of the brain revealed acute infarction in the right aspect of the cerebral peduncle and chronic lacunars infarct in the right thalamus with diffusion restriction. Repeated MRI after 5 months revealed diffuse loss of brain volume. The blood workup showed high inflammatory markers and significantly low adenosine deaminase 2 (ADA2) level. After being on corticosteroid and anticoagulant treatments, she suffered from a recurrent episode of cerebral infarction, after which she was commenced on tumor necrosis factor (TNF)-antagonist therapy in addition to monthly fresh plasma infusion. Thereafter, there was no cerebral insult reported for >18 months. The genetic study of the child and her parents revealed a homozygous mutation c. 336C>A, p. (His112Gln) in the CECR1 gene, and her parents were heterozygous for the same variant. This variant was not previously reported in literature. We would suggest to link this novel variant c. 336C>A, p. (His112Gln) of CECR1 gene mutation with the clinical picture, along with the positive response to TNF-antagonist therapy in the era of ADA2 deficiency syndrome.
Keywords: Adenosine deaminase deficiency, anti-tumor necrosis factor therapy, cat eye syndrome chromosome region, candidate 1 mutation, livedo reticularis
|How to cite this article:|
Al Mosawi ZS, Abduljawad HO, Busehail MY, Al Moosawi BM. Adenosine deaminase 2 deficiency with a novel variant of CECR1 gene mutation: Responding to tumor necrosis factor antagonist therapy. Indian J Rheumatol 2019;14:236-40
|How to cite this URL:|
Al Mosawi ZS, Abduljawad HO, Busehail MY, Al Moosawi BM. Adenosine deaminase 2 deficiency with a novel variant of CECR1 gene mutation: Responding to tumor necrosis factor antagonist therapy. Indian J Rheumatol [serial online] 2019 [cited 2020 Jan 27];14:236-40. Available from: http://www.indianjrheumatol.com/text.asp?2019/14/3/236/265813
| Introduction|| |
The bi-allelic loss of function mutations in the CECR1 (cat eye syndrome chromosome region, candidate 1) gene, mapped to chromosome 22q11.1., has resulted in a deficiency of an extracellular enzyme called adenosine deaminase 2 (ADA2). ADA2 deficiency has been associated with a loss in the integrity of the endothelial cells and inflammation of various organs and tissues, mainly blood vessels., Deficiency of ADA2 (DADA2) syndrome is characterized by recurrent fever, early-onset stroke, and hypogammaglobulinemia.,, Large phenotypic variability in patients with ADA2 deficiency was detected even among patients having an identical homozygous CECR1 mutation.,
We present the case of a 4-year-old child with recurrent cerebral infarction, mottled skin discoloration, and a new variant of homozygous CECR1 gene mutation.
The health research committee at the Ministry of Health in the Kingdom of Bahrain has approved the review of the case, and formal written consent was obtained from the patient's guardians.
| Case Report|| |
A 4-year-old girl presented with a history of abdominal pain, vomiting, and skin rash for 10 days, followed by visual loss in her right eye and unsteady gait. Past medical history revealed an episode of external ophthalmoplegia of the right eye few months ago, which resolved after a few hours. She was born out of a consanguineous marriage, first-degree parents [Figure 1]. The family history was negative for any medical diseases, and the patient has a younger sister who is well. On examination, her vital signs were stable, including her blood pressure. Neurological assessment revealed left-sided weakness, hypertonic and exaggerated deep tendon reflexes (DTRs) in the lower limb, together with sustained clonus. Apart from the third cranial nerve, other cranial nerves were intact. The eyes had normal reacting pupils and fundi. However, the right eye showed loss of adduction (exotropia) and upward gaze (hypotropia), whereas the left eye expressed nystagmus in the lateral gaze. Rest of the eye movements were intact, and no ptosis or proptosis was observed. Skin examination revealed reticular, erythematous, tiny circles that resembled livedo reticularis in the medial edge of the soles and blue toes, violaceous skin lesions in both palms and distal pulp of the fingers, and a swollen right ankle [Figure 2]. Systemic examination was unremarkable for any additional findings.
|Figure 2: (a) Livedo reticularis and purplish discoloration of the big toe. (b) A similar rash on the dorsum of the foot with a slightly swollen ankle|
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Brain images showed unremarkable computed tomography scan findings, but magnetic resonance imaging (MRI) showed acute infarction in the right aspect of the cerebral peduncle including the oculomotor and red nucleus. In addition, a chronic lacunar infarct in the right thalamus with diffusion restriction was noted [Figure 3]; magnetic resonance angiography and magnetic resonance venography were normal. Doppler ultrasound of the carotid and vertebral arterial systems showed no evidence of stenosis. Abdominal sonography revealed an enlarged spleen.
|Figure 3: (a) Axial diffusion-weighted image showing acute infarction in the right aspect of cerebral peduncle (mid brain) in the area of the oculomotor and red nucleus. (b) Axial T2 weighted-image showing a chronic infarct in the right thalamus|
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Laboratory results revealed a hemoglobin (Hb) level of 8.6 g/dl, white blood cells of 9 109/I, and a platelet count of 445 109/I. Coagulation profile was normal. Hb electrophoresis, Factor VIII, anti-thrombin III assay, and Factor V Leiden gene mutation were all normal. Protein C factor, protein S factor, and homocysteine level were normal. Serology screening was negative for anti-nuclear antibodies, anti-dsDNA antibodies, anti-neutrophilic cytoplasmic antibodies, and anti-cardiolipin antibodies.
Erythrocyte sedimentation rate was 96 mm/h (N: <20) and C-reactive protein (CRP) was 122 mg/l (N: 1–3). Cerebrospinal fluid biochemistry and culture were negative. Metabolic screening was normal. Viral causes were ruled out. Immunology screening revealed low IgM level (0.3 g/l [N: 0.5–2]) but normal IgA and IgG. Lymphocyte subsets were normal for T and B lymphocytes.
Based on the impression of thrombotic episode, she received conservative treatment and was started on prophylactic dose of aspirin. Following that, the child was gradually improving. Three months later, she was able to walk, and her eye squint and vision acuity (VA) were also improving. However, 5 months after the episode, the patient exhibited a high-grade fever, together with subtle right-sided weakness. Laboratory results showed low Hb (7.5 g/dl) and high CRP (102 mg/dl). Repeated MRI brain at this stage showed a new acute infarction in the left cerebral peduncle with extension to the left hypothalamus, and also revealed interval diffuse loss of brain volume [Figure 4]. Based on the impression of acute vasculitis, she was started on prednisolone 1.2 mg/kg/day. The following 5 months, the child's general condition was steadily improving in addition to a significant reduction in inflammatory markers (CRP: 20 mg/l) and a rise in the Hb level (Hb: 11.5 g/dl).
|Figure 4: (a) Axial diffusion-weighted image showing focus of restricted diffusion of the left side of the mid brain indicative of acute infarction. (b) Another focus of restricted diffusion of the left hypothalamus|
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At the age of 4 years and 10 months of age, our patient suffered from a new episode of right-sided weakness and a reduction in her VA. The new MRI brain images revealed multiple acute infarcts of bilateral cerebral peduncles extending to the hypothalamus and other infarcts in the left thalamus regions together with high inflammatory markers [Figure 5]. ADA2 deficiency syndromes were suspected, and ADA2 enzyme activity testing revealed a significantly low level (<4.0 [N: 4–20 U/L]). The level was repeated 1 month after the cerebral insult, and the result was still significantly low.
|Figure 5: (a) Axial diffusion-weighted image showing bilateral restricted diffusion of the hypothalamus indicative of acute infarction. (b) Another focus of restricted diffusion of the area of the left thalamus and left basal ganglia|
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For this episode, she received methylprednisolone 10 mg/kg/day for 2 days followed by oral prednisolone. Anti-tumor necrosis factor (TNF) therapy (etanercept) was started at a dose of 0.8 mg/kg/week in addition to low-dose aspirin. She was also commenced to receive monthly fresh frozen plasma (FFP) transfusion. Few weeks later, this patient had a dramatic improvement in her clinical condition with decline of her inflammatory markers. Few months after this episode, she remained clinically stable while the prednisolone dose was gradually tapered to 5 mg/day. On follow-up, the child's physical and intellectual development was gradually improving. Eighteen months after being on this treatment, at the age of 6½ years, this girl did not report any brain insult; the neurological assessment revealed remarkable improvement in her muscle tone and DTR, along with normal gait. The left eye was dominant with slightly reduced VA, whereas the right eye showed a posterior sub-capsular cataract. Exotropia and hypotropia (1/4 and 2/4 respectively).
The child's condition was maintained for >18 months on weekly etanercept injections (same dose), in conjunction with a monthly FFP transfusion, low-dose prednisolone, and prophylactic dose of aspirin.
Sanger sequencing analysis of the ADA2 gene (NM_001282225.1; Chr. 22) was performed. The reported variant was classified as per the international recommendations (PMID: 25741868) and was confirmed by independent polymerase chain reaction and sequencing.
| Results|| |
Our patient carried a homozygous mutation identified as c. 336C>A, p. (His112Gln) in the CECR1 gene encoding for ADA2. However, this new variant was not reported in literature, and is not described in the population databases (dbSNP, ESP, and gnomAD). It affects a highly conserved amino acid, and the bioinformatics analysis suggests that this variant is predicted to be deleterious.
Upon segregation analysis, the familial variant c. 336C>A, p. (His112Gln) was detected in heterozygosity in both the parents of the proband (CGC Genetics laboratory, Test ID: CGC 852715 and CGC 852697), and the genetic testing for the other asymptomatic sibling was normal, along with a normal ADA2 enzyme assay (CGC Genetics laboratory, Test ID: CGC 852695).
| Discussion|| |
Deficiency of ADA2 (DADA2) is a rare autosomal recessive condition resulting from mutations in CECR1 gene. The phenotype of DADA2 may overlap with the clinical spectrum of polyarteritis nodosa which is a disorder that causes inflammation of the blood vessels throughout the body (systemic vasculitis).,, The classical feature of ADA2 is characterized by chronic or recurrent systemic inflammation with fever, livedo reticularis, and possibly associated with an immunodeficiency of variable severity.,,
Most of the DADA2-associated mutations are either novel or found at a low allele frequency (<0.001) in public databases. Majority of them are missense variants, although genomic deletion, nonsense, and splicing mutations have also been reported.
A serial of novel CECR1 mutations in patients with DADA2 were recently discovered. A 3-month-old child with ADA2 deficiency syndrome and compound heterozygous CECR1 gene mutation (c.1211T>C, p. Phe404Ser, and c.1114G>A, p. Val372Met) developed gangrene of the fingers followed by infarction in the right thalamus. Two affected sisters with DADA2 presented only with fever, neutropenia, and/or lymphopenia without cardinal features of ADA2 deficiency syndrome. They were noticed to carry compound heterozygous CECR1 gene mutation at positions 506 (exon 2) and 1057 (exon 6) of the coding sequence of ADA2 (c.506G>A, c. 1057T>C), resulting in amino acid substitutions in p. Arg169Gln and p. Tyr353His in ADA2 (NM_001282225.1), respectively. Furthermore, an adult female with ADA2 deficiency presented with clinical features that mimic anti-phospholipid syndrome and carried a compound heterozygous genotype at the CECR1 gene. She had a p. (Leu188Val) missense variant (rs765219776) at exon 4 and a c. 753+2T>A variant at intron 4 of the CECR1 gene.,,
Nineteen patients with ADA2 deficiency were described with CECR1 mutation (G47R/G47R) and a wide clinical spectrum ranging from mild and skin-limited disease to severe and critical disease with multiorgan involvement. Another identical homozygous R169Q mutation in CECR1 was detected in nine ADA2-deficient patients with significant clinical heterogeneity. However, ADA2 level was significantly lower in cases with recurrent strokes.
Consistent with the low IgM level, which had been reported in other patients with DADA2, our patient had low IgM level. Hypogammaglobulinemia was reported in patients with DADA2.,, Immunological assessment of patients with DADA2 revealed normal T-cell function. However, when mononuclear cells from peripheral blood (PB) of patients with DADA2 were cultured for 48 h without stimulation, spontaneous B-cell death was observed in higher rates in the patient sample in comparison to healthy controls. Further, when compared with healthy controls, samples from the patients with DADA2 contained less memory B-cells in PB and a decrease in terminal differentiation of B-cells and immunoglobulin-secreting cells after T-cell-dependent stimulation.
Another study mentioned an observation of absent plasma ADA2 activity in an adult with hypogammaglobulinemia and compound heterozygous ADA2 mutations who had recurrent respiratory infection. Furthermore, an inverse correlation between CRP and immunoglobulin levels was also detected in one patient, suggesting that the inflammatory milieu of DADA2 may directly compromise the B-cell compartment.
Alternatively, no significant impairments in the T-cell compartment were detected in patients with DADA2. The T-cell activation, mitogen-induced proliferation, and ex vivo cytokine production by T-cells were comparable in patients with DADA2 and controls. Because specific defects in T-cell function are not apparent, infection related to suboptimal T-cell function in patients with DADA2 may be better explained by generalized lymphopenia.
A previous study showed at least 60% of patients with ADA2 deficiency having central nervous system involvement which is mostly present in the form of one or more cerebral strokes, or, less commonly, a hemorrhagic stroke. The condition tends to show a predilection for deep gray matter involvement at the basal ganglia, the posterior fossa, and the brain stem. It tends to spare the subcortical white matter., Furthermore, progressive atrophy of the brain matter was clearly demonstrated in our case over a short period of 5 months, which is the duration between her first and second attacks.
There is no consensus on the treatment of patients with DADA2. Corticosteroids have been used to control disease progression with variable success. On the other hand, the most common immunosuppressive drugs (azathioprine, methotrexate, and tacrolimus) were found to be ineffective.,,,,
Biologic treatments have a role in managing cases with ADA2 deficiency disease. Anti-TNF drugs (etanercept, adalimumab, and infliximab) have been used in ten patients with DADA2 with complete response in eight, even after the failure of immunosuppressive treatment. TNF inhibitors also control fever episodes and vasculopathy and prevent strokes in patients with ADA2 deficiency syndrome. TNF inhibitors also contribute to an encouraging result in a previously reported small case series of patients with DADA2.,, Moreover, anti-TNF agents were successful in treating patients with DADA2 and focal segmental glomerulonephritis together with plasmapheresis, and are highly recommended as first-line therapy to treat vasculitis.,
Anti-interleukin 6 (tocilizumab) was also effective in suppressing inflammation in patients with DADA2 presenting with a Castleman-like clinical picture. However, this treatment was not effective in preventing recurrent strokes in another DAD2 patient.,
Additionally, because ADA2 is found in the plasma, these patients may benefit from FFP for substituting ADA2 activity. Furthermore, immunoglobulin replacement is effective in treating patients suffering from DADA2 with hypogammaglobulinemia., Hematopoietic stem cell transplantation (HSCT) was proposed as an effective therapy to treat patients with DADA2 by providing ADA2-producing monocytes and therefore normalizing the plasmatic levels of the enzyme. HSCT was successfully used to control disease manifestations in patients with ADA2 deficiency syndrome.,,,
| Conclusion|| |
We described a child with recurrent strokes, acute and chronic lacunar infarcts, low IgM level and loss of brain volume that responded well to a TNF-antagonist agent. Detection of novel homozygous CECR1 mutation [c.336C>A, p. (His112Gln)] in this child, may contribute to knowledge on the mutational spectrum associated with ADA2 deficiency syndrome. Awareness of the diverse manifestations of ADA2 deficiency syndrome, could warrant early treatment, and therefore prevents recurrent strokes and improves clinical outcomes.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]