Evaluation and Management of Deficiency of Adenosine Deaminase 2: An International Consensus Statement.

Importance: Deficiency of adenosine deaminase 2 (DADA2) is a recessively inherited disease characterized by systemic vasculitis, early-onset stroke, bone marrow failure, and/or immunodeficiency affecting both children and adults. DADA2 is among the more common monogenic autoinflammatory diseases, with an estimate of more than 35 000 cases worldwide, but currently, there are no guidelines for diagnostic evaluation or management. Objective: To review the available evidence and develop multidisciplinary consensus statements for the evaluation and management of DADA2. Evidence Review: The DADA2 Consensus Committee developed research questions based on data collected from the International Meetings on DADA2 organized by the DADA2 Foundation in 2016, 2018, and 2020. A comprehensive literature review was performed for articles published prior to 2022. Thirty-two consensus statements were generated using a modified Delphi process, and evidence was graded using the Oxford Center for Evidence-Based Medicine Levels of Evidence. Findings: The DADA2 Consensus Committee, comprising 3 patient representatives and 35 international experts from 18 countries, developed consensus statements for (1) diagnostic testing, (2) screening, (3) clinical and laboratory evaluation, and (4) management of DADA2 based on disease phenotype. Additional consensus statements related to the evaluation and treatment of individuals with DADA2 who are presymptomatic and carriers were generated. Areas with insufficient evidence were identified, and questions for future research were outlined. Conclusions and Relevance: DADA2 is a potentially fatal disease that requires early diagnosis and treatment. By summarizing key evidence and expert opinions, these consensus statements provide a framework to facilitate diagnostic evaluation and management of DADA2.

Comprehensive analysis of ADA2 genetic variants and estimation of carrier frequency driven by a function-based approach.

BACKGROUND: Deficiency of adenosine deaminase 2 (DADA2) is an autoinflammatory disease caused by deleterious ADA2 variants. The frequency of these variants in the general population, and hence the expected disease prevalence, remain unknown. OBJECTIVE: We aimed to characterize the functional impact and carrier frequency of ADA2 variants. METHODS: We performed functional studies and in silico analysis on 163 ADA2 variants, including DADA2-associated variants and population variants identified in the Genome Aggregation Database. We estimated the carrier rate using the aggregate frequency of deleterious variants. RESULTS: Functional studies of ADA2 variants revealed that 77 (91%) of 85 of DADA2-associated variants reduced ADA2 enzymatic function by >75%. Analysis of 100 ADA2 variants in the database showed a full spectrum of impact on ADA2 function, rather than a dichotomy of benign versus deleterious variants. We found several in silico algorithms that effectively predicted the impact of ADA2 variants with high sensitivity and specificity, and confirmed a correlation between the residual function of ADA2 variants in vitro and the plasma ADA2 activity of individuals carrying these variants (n = 45; r = 0.649; P < .0001). Using <25% residual enzymatic activity as the cutoff to define potential pathogenicity, integration of our results with the database population data revealed an estimated carrier frequency of at least 1 in 236 individuals, corresponding to an expected DADA2 disease prevalence of ~1 in 222,000 individuals. CONCLUSIONS: Functional annotation guides the interpretation of ADA2 variants to create a framework that enables estimation of DADA2 carrier frequency and disease prevalence.

Deficiency of Adenosine Deaminase 2 in Adults and Children: Experience From India.

OBJECTIVE: Deficiency of adenosine deaminase 2 (DADA2) is a potentially fatal monogenic syndrome characterized by variable manifestations of systemic vasculitis, bone marrow failure, and immunodeficiency. Most cases are diagnosed by pediatric care providers, given the typical early age of disease onset. This study was undertaken to describe the clinical phenotypes and treatment response both in adults and in children with DADA2 in India. METHODS: A retrospective analysis of pediatric and adult patients with DADA2 diagnosed at various rheumatology centers across India was conducted. Clinical characteristics, diagnostic findings, and treatment responses were analyzed in all subjects. RESULTS: In total, 33 cases of DADA2 were confirmed in this cohort between April 2017 and March 2020. Unlike previous studies, nearly one-half of the confirmed cases presented during adulthood. All symptomatic patients exhibited features of vasculitis, whereas constitutional symptoms and anemia were more common in pediatric patients. Cutaneous and neurologic involvement were common, and 18 subjects had experienced at least one stroke. In addition, the clinical spectrum of DADA2 was expanded by recognition of novel features in these patients, including pancreatic infarction, focal myocarditis, and diffuse alveolar hemorrhage. Treatment with tumor necrosis factor inhibitors (TNFi) was initiated in 25 patients. All of the identified disease manifestations showed marked improvement after initiation of TNFi, and disease remission was achieved in 19 patients. Two cases were complicated by tuberculosis infection, and 2 deaths were reported. CONCLUSION: This report presents the first case series of patients with DADA2 from India, diagnosed by adult and pediatric care providers. The findings raise awareness of this syndrome, particularly with regard to its presentation in adults.

Genotype and functional correlates of disease phenotype in deficiency of adenosine deaminase 2 (DADA2).

BACKGROUND: Deficiency of adenosine deaminase 2 (DADA2) is a syndrome with pleiotropic manifestations including vasculitis and hematologic compromise. A systematic definition of the relationship between adenosine deaminase 2 (ADA2) mutations and clinical phenotype remains unavailable. OBJECTIVE: We sought to test whether the impact of ADA2 mutations on enzyme function correlates with clinical presentation. METHODS: Patients with DADA2 with severe hematologic manifestations were compared with vasculitis-predominant patients. Enzymatic activity was assessed using expression constructs reflecting all 53 missense, nonsense, insertion, and deletion genotypes from 152 patients across the DADA2 spectrum. RESULTS: We identified patients with DADA2 presenting with pure red cell aplasia (n = 5) or bone marrow failure (BMF, n = 10) syndrome. Most patients did not exhibit features of vasculitis. Recurrent infection, hepatosplenomegaly, and gingivitis were common in patients with BMF, of whom half died from infection. Unlike patients with DADA2 with vasculitis, patients with pure red cell aplasia and BMF proved largely refractory to TNF inhibitors. ADA2 variants associated with vasculitis predominantly reflected missense mutations with at least 3% residual enzymatic activity. In contrast, pure red cell aplasia and BMF were associated with missense mutations with minimal residual enzyme activity, nonsense variants, and insertions/deletions resulting in complete loss of function. CONCLUSIONS: Functional interrogation of ADA2 mutations reveals an association of subtotal function loss with vasculitis, typically responsive to TNF blockade, whereas more extensive loss is observed in hematologic disease, which may be refractory to treatment. These findings establish a genotype-phenotype spectrum in DADA2.

Changing intraoperative parathyroid hormone collection sites from peripheral to central does not affect predictive accuracy during minimally invasive parathyroidectomy.

BACKGROUND: Intraoperative parathyroid hormone (ioPTH) monitoring (IPM) is vital to minimally invasive parathyroidectomy. Techniques vary in assay sampling, potentially affecting predictive accuracy of operative success. Initial guidelines were established using peripheral sites, but central sites may be preferred or necessary when peripheral access is not feasible. We hypothesize that changing collection sites from preexcision peripheral sites to postexcision central sites would not affect IPM accuracy. METHODS: Analysis of 64 consecutive patients who underwent parathyroidectomy for primary hyperparathyroidism was undertaken. PTH assays were collected simultaneously from a peripheral vein (PV) and central vein (CV) preexcision and at a 10-min interval after initial parathyroid excision. IPM success was defined as PTH decrease ≥50% 10 min after initial excision. Predictive accuracy was determined by the need to resect another abnormal gland and biochemical normalization in the postoperative clinic. Receiver operating characteristic (ROC) method with area under the curve (AUC) compared diagnostic accuracy of different assay approaches. RESULTS: Centrally, a statistically higher mean pre- and postexcision ioPTH of 391 pg/ml and 58 pg/ml was found compared with peripheral means of 156 pg/ml and 49 pg/ml, respectively (p < 0.001). The AUC when changing from a PV preexcision to a CV postexcision ioPTH was 0.89, comparable to AUC for peripheral or central assay collections alone (AUC = 0.83 and 0.85, respectively). CONCLUSIONS: This study suggests that altering collection sites does not alter assay validity. In cases where peripheral sampling is compromised, changing from a peripheral to central sites will not likely alter the predictive accuracy of IPM significantly.

Malignant pheochromocytoma of the organ of Zuckerkandl requiring aortic and vena caval reconstruction.

OBJECTIVE: To describe a case of a malignant pheochromocytoma located in the organ of Zuckerkandl that required aortic and vena caval resection and reconstruction. METHODS: We present a case report that includes clinical, laboratory, and radiographic data as well as photographs, results from pathology, and a brief review of the literature. RESULTS: A 46-year-old man was referred for evaluation of a 1.4-cm left adrenal mass incidentally discovered on an abdominopelvic computed tomography (CT) scan. Subsequent laboratory evaluation revealed the following values: urine norepinephrine, 252 microg/24 h; urine normetanephrine, 1122 microg/24 h; urine metanephrine, 162 microg/24 h; urine epinephrine, 7 microg/24 h; urine vanillylmandelic acid, 8 mg/24 h; and plasma metanephrine, 98 pg/ mL. Imaging characteristics of the left adrenal mass were consistent with a benign adenoma, but CT also demonstrated a hypervascular para-aortic mass. 123I-metaiodo-benzylguanidine scanning with fusion CT imaging demonstrated increased radiopharmaceutical uptake within the para-aortic mass consistent with a paraganglioma in the organ of Zuckerkandl. Findings from CT angiography of the abdomen and pelvis suggested aortic involvement and vena caval thrombus. The mass was excised en bloc, including portions of the aorta, inferior vena cava, and right ureter. The aorta and vena cava were reconstructed using Dacron grafts. The remaining right ureter and kidney were removed to avoid the possibility of a urine leak from an ureteroureterostomy. Final pathologic and operative findings confirmed a malignant pheochromocytoma of the organ of Zuckerkandl with invasion into the wall of the inferior vena cava and tumor thrombus extending into the lumen. CONCLUSION: Malignant pheochromocytoma of the organ of Zuckerkandl involving the aorta and inferior vena cava is exceedingly rare, and although surgical resection and reconstruction can be radical and aggressive, this treatment offers the only chance for cure.

Serum thyroglobulin, high-resolution ultrasound, and lymph node thyroglobulin in diagnosis of differentiated thyroid carcinoma nodal metastases.

CONTEXT: Clinically enlarged cervical lymph nodes in patients with a history of thyroid cancer are usually assessed by fine-needle aspiration biopsy (FNAB) followed by cytology with or without tissue core. Thyroglobulin (Tg) is frequently elevated in malignant FNAB needle-wash specimens and may possibly augment or replace cytology. Furthermore, the combination of undetectable serum Tg and an innocuous ultrasound might altogether obviate the need for biopsy. OBJECTIVES: The objectives of the study were to: 1) determine an appropriate diagnostic cutoff for Tg levels in FNAB; 2) assess the diagnostic performance at this cutoff; and 3) compare serum Tg and FNAB needle-wash Tg levels to determine whether serum Tg levels predict positive Tg FNAB. DESIGN: This was a retrospective study of 122 FNAB samples in 88 athyrotic thyroid cancer patients. RESULTS: Fifty of 52 nonmalignant FNAB samples (96.2%) had Tg 1 ng/ml or less. All 70 malignant FNAB had Tg greater than 1 ng/ml. Of 103 specimens with diagnostic cytology, five (4.9%) had discordant Tg results; in four of these FNAB Tg was concordant with the final diagnosis. Eighteen of 19 (94.7%) FNAB with nondiagnostic (n = 16) or absent (n = 3) cytology were correctly classified by FNAB needle-wash Tg. Undetectable (<0.1 ng/ml) serum Tg was associated with a negative diagnosis in 21 of 23 biopsies (91.7%); the two cancer-positive samples were both serum Tg autoantibody positive and classified as suspicious by ultrasonography. CONCLUSIONS: Nodal FNAB needle-wash Tg measurements complement cytology in thyroid cancer follow-up and might substitute for it. The combination of unremarkable ultrasonography and an undetectable serum Tg in Tg autoantibody-negative patients might obviate the need for FNAB.

Central venous sampling for intraoperative parathyroid hormone monitoring: are peripheral guidelines applicable?

Intraoperative parathyroid hormone (PTH) monitoring has become an integral adjunct to minimally invasive parathyroidectomy. Guidelines for predicting therapeutic excision of all hyperactive parathyroid tissue have been routinely based on peripheral blood samples drawn at various time intervals. Whether these same guidelines can be used to predict success based on central blood draws has not been established. The authors wanted to evaluate whether peripheral criteria were applicable when PTH levels were drawn from a central location. Simultaneous peripheral venous (PV) and central venous (CV) PTH samples were drawn from 64 patients undergoing cervical exploration for primary hyperparathyroidism. Median preexcision PTH was significantly higher centrally at 165 pg/mL (interquartile range [IQR], 101-391 pg/mL) versus peripherally 102 pg/mL (interquartile range, 73-156 pg/mL, P < 0.0001). Postexcision PTH was slightly greater in CV (38 pg/mL; IQR, 24-62) than in PV (29 pg/mL; IQR, 22-51; P < 0.0001). The decrease in intraoperative PTH was compared after excision of an initial gland. Fifty-four of the 64 patients had all hyperfunctioning parathyroid tissue removed after initial gland resection. Pre- to postexcision ratios for CV and PV were compared using receiver operating characteristic curve methods, and summarized by area under the curve (AUC). PV (AUC = 0.85) appears to be a slightly more sensitive discriminator than CV (AUC = 0.83), although the difference is not statistically significant (P = 0.5). Despite higher absolute values for CV, both peripheral and central sample sites accurately predict outcomes based on established guidelines for intraoperative PTH monitoring.