Prevalence and Risk Factors of Post-Acute Sequela of COVID-19 in Adults with Systemic Autoimmune Rheumatic Diseases.

OBJECTIVE: Incidence and manifestations of post-acute sequelae of COVID-19 (PASC) are poorly defined among immunosuppressed populations. We reported, phenotyped, and assessed risk factors for PASC in adults with systemic autoimmune diseases. METHODS: Persons ≥18 years with systemic autoimmune diseases were recruited into a national, prospective cohort of SARS-CoV-2 vaccination between 12/2020-4/2021. Serial surveys assessed vaccination status, SARS-CoV-2 infection incidence, and disease flares. Participants reporting SARS-CoV-2 infection received a questionnaire assessing symptom duration, severity, and quality of life (QoL) impact; PASC was defined as ≥1 symptom persisting for >12 weeks. PASC syndromes were mapped via overlapping symptom domains. Characteristics were compared between participants who did versus did not report PASC. RESULTS: Among 1615 participants, 590 (36.5%) reported SARS-CoV-2 infection and were sent PASC surveys, 299 (50.7%) of whom responded >12 weeks following reported infection. Respondents were 1.62% female, 90.2% white, median (IQR) age 48(40-60) years with median (IQR) 3 (2-3) vaccine doses at time of first infection. Common diagnoses included inflammatory arthritis (38.5%) and inflammatory bowel disease (14.4%). 89/299 (29.8%) reported PASC, with the most reported symptom domain being neurological/psychological (83.1%); 84% reported an impact on QoL. Participants with PASC reported lower number of preceding vaccines (median [IQR] 2[2-3] versus 3[2-3]; p<0.001) and more reinfections (16.9% versus 5.7%; p=0.004). CONCLUSION: 29.8% of persons with systemic autoimmune disease in a large real-world cohort reported PASC, often affecting QoL. Preceding vaccination may reduce PASC, whereas multiple infections may increase risk, supporting ongoing booster vaccine campaigns and efforts to limit breakthrough infections.

Efficacy of Tocilizumab in Patients Hospitalized with Covid-19.

BACKGROUND: The efficacy of interleukin-6 receptor blockade in hospitalized patients with coronavirus disease 2019 (Covid-19) who are not receiving mechanical ventilation is unclear. METHODS: We performed a randomized, double-blind, placebo-controlled trial involving patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, hyperinflammatory states, and at least two of the following signs: fever (body temperature >38°C), pulmonary infiltrates, or the need for supplemental oxygen in order to maintain an oxygen saturation greater than 92%. Patients were randomly assigned in a 2:1 ratio to receive standard care plus a single dose of either tocilizumab (8 mg per kilogram of body weight) or placebo. The primary outcome was intubation or death, assessed in a time-to-event analysis. The secondary efficacy outcomes were clinical worsening and discontinuation of supplemental oxygen among patients who had been receiving it at baseline, both assessed in time-to-event analyses. RESULTS: We enrolled 243 patients; 141 (58%) were men, and 102 (42%) were women. The median age was 59.8 years (range, 21.7 to 85.4), and 45% of the patients were Hispanic or Latino. The hazard ratio for intubation or death in the tocilizumab group as compared with the placebo group was 0.83 (95% confidence interval [CI], 0.38 to 1.81; P = 0.64), and the hazard ratio for disease worsening was 1.11 (95% CI, 0.59 to 2.10; P = 0.73). At 14 days, 18.0% of the patients in the tocilizumab group and 14.9% of the patients in the placebo group had had worsening of disease. The median time to discontinuation of supplemental oxygen was 5.0 days (95% CI, 3.8 to 7.6) in the tocilizumab group and 4.9 days (95% CI, 3.8 to 7.8) in the placebo group (P = 0.69). At 14 days, 24.6% of the patients in the tocilizumab group and 21.2% of the patients in the placebo group were still receiving supplemental oxygen. Patients who received tocilizumab had fewer serious infections than patients who received placebo. CONCLUSIONS: Tocilizumab was not effective for preventing intubation or death in moderately ill hospitalized patients with Covid-19. Some benefit or harm cannot be ruled out, however, because the confidence intervals for efficacy comparisons were wide. (Funded by Genentech; ClinicalTrials.gov number, NCT04356937.).

Association between anti-SSSCA1 antibodies and cancer in systemic sclerosis.

OBJECTIVE: To define the clinical phenotype of SSc patients with antibodies against Sjogren's syndrome (SS)/scleroderma autoantigen 1 (SSSCA1), and to examine the association between these antibodies and cancer in SSc patients. METHODS: We conducted a case-control study using data from 209 patients with SSc and cancer, and 205 SSc patients without cancer. All were randomly selected from the Johns Hopkins Scleroderma Center Research Registry. Antibodies against SSSCA1 were assayed by immunoprecipitation of 35S-methionine-labelled protein generated by in vitro transcription and translation. We performed logistic regression analysis to examine the relationship between anti-SSSCA1 antibodies and cancer. RESULTS: Among the 414 study patients, 31 (7%) were anti-SSSCA1 antibody positive. Antibody-positive patients were more likely to have severe RP, a lower minimum ejection fraction, a trend towards more severe heart involvement and a lower baseline diffusing capacity of the lungs for carbon monoxide percent predicted than anti-SSSCA1-negative patients. Patients with cancer were significantly more likely to be anti-SSSCA1 positive compared with those without cancer [22/209 (11%) vs 9/205 (4%), respectively; P = 0.018]. Among patients with cancer, there was a trend towards longer cancer-SSc interval in anti-SSSCA1-positive patients compared with anti-SSSCA1-negative patients. Patients with anti-SSSCA1 antibodies had an increased adjusted risk of cancer (odds ratio 2.46, 95% CI 1.06, 5.70) compared with anti-SSSCA1-negative patients. CONCLUSIONS: These data suggest anti-SSSCA1 antibody status may be of utility as a cancer biomarker in SSc. Anti-SSSCA1-positive patients with SSc may be more likely to have severe Raynaud's and cardiac involvement.

Coronavirus disease 2019 outcomes among patients with rheumatic diseases 6 months into the pandemic.

OBJECTIVE: In earlier studies, patients with rheumatic and musculoskeletal disease (RMD) who got infected with COVID-19 had a higher risk of mechanical ventilation than comparators. We sought to determine COVID-19 outcomes among patients with RMD 6 months into the pandemic. METHODS: We conducted a cohort study at Mass General Brigham in Boston, Massachusetts, of patients with RMD matched to up to five comparators by age, sex and COVID-19 diagnosis date (between 30 January 2020 and 16 July 2020) and followed until last encounter or 18 August 2020. COVID-19 outcomes were compared using Cox regression. Risk of mechanical ventilation was compared in an early versus a recent cohort of patients with RMD. RESULTS: We identified 143 patients with RMD and with COVID-19 (mean age 60 years; 76% female individuals) and 688 comparators (mean age 59 years; 76% female individuals). There were no significantly higher adjusted risks of hospitalisation (HR: 0.87, 95% CI: 0.68-1.11), intensive care unit admission (HR: 1.27, 95% CI: 0.86-1.86), or mortality (HR: 1.02, 95% CI: 0.53-1.95) in patients with RMD versus comparators. There was a trend towards a higher risk of mechanical ventilation in the RMD cohort versus comparators, although not statistically significant (adjusted HR: 1.51, 95% CI: 0.93-2.44). There was a trend towards improvement in mechanical ventilation risk in the recent versus early RMD cohort (10% vs 19%, adjusted HR: 0.44, 95% CI: 0.17-1.12). CONCLUSIONS: Patients with RMD and comparators had similar risks of poor COVID-19 outcomes after adjusting for race, smoking and comorbidities. The higher risk of mechanical ventilation in the early RMD cohort was no longer detected in a recent cohort, suggesting improved management over time.

The association of smoking with immunoglobulin G4-related disease: a case-control study.

OBJECTIVE: To evaluate the association between cigarette smoking and the odds of IgG4-related disease (IgG4-RD). METHODS: We performed a case-control study of patients with IgG4-RD compared in a 1:5 ratio with age-, race- and sex-matched controls. We included cases evaluated at the Massachusetts General Hospital, a hospital within the Mass General Brigham (MGB) System. Controls were identified from the MGB Biobank. Smoking status at the date of IgG4-RD diagnosis or corresponding index date was determined. Conditional logistic regression was used to estimate the association between cigarette smoking and the odds of having IgG4-RD. RESULTS: There were 234 IgG4-RD cases and 1170 controls. The mean age (59 years), sex (62% male) and race (75% white) were well balanced. IgG4-RD cases were more likely to be current smokers compared with controls [25 (11%) vs 70 (6%); odds ratio (OR) 1.79 (95% CI 1.08, 2.95)]. This association was strongest among female cases [13 (14%) vs 19 (4%);, OR 3.79 (95% CI 1.71, 8.39)] and those with retroperitoneal fibrosis [RPF; 13 (28%) vs 13 (6%);, OR 6.93 (95% CI 2.78, 17.26)] or normal IgG4 concentrations [21 (21%) vs 21 (4%); OR 6.22 (95% CI 3.09, 12.49)]. When RPF cases were excluded, there was no longer an association between current smoking and the odds of having IgG4-RD [12 (6%) vs 57 (6%); OR 0.95 (95% CI 0.49, 1.86)]. CONCLUSION: Being a current smoker is associated with greater odds of having IgG4-RD, especially among women and those with RPF or normal IgG4 concentrations. Current smoking is the first recognized modifiable risk factor for IgG4-RD.

Clinical characteristics and outcomes of patients with coronavirus disease 2019 (COVID-19) and rheumatic disease: a comparative cohort study from a US 'hot spot'.

OBJECTIVE: To investigate differences in manifestations and outcomes of coronavirus disease 2019 (COVID-19) infection between those with and without rheumatic disease. METHODS: We conducted a comparative cohort study of patients with rheumatic disease and COVID-19 (confirmed by severe acute respiratory syndrome coronavirus 2 PCR), compared in a 1:2 ratio with matched comparators on age, sex and date of COVID-19 diagnosis, between 1 March and 8 April 2020, at Partners HealthCare System in the greater Boston, Massachusetts area. We examined differences in demographics, clinical features and outcomes of COVID-19 infection. The main outcomes were hospitalisation, intensive care admission, mechanical ventilation and mortality. RESULTS: We identified 52 rheumatic disease patients with COVID-19 (mean age, 63 years; 69% female) and matched these to 104 non-rheumatic disease comparators. The majority (39, 75%) of patients with rheumatic disease were on immunosuppressive medications. Patients with and without rheumatic disease had similar symptoms and laboratory findings. A similar proportion of patients with and without rheumatic disease were hospitalised (23 (44%) vs 42 (40%)), p=0.50) but those with rheumatic disease required intensive care admission and mechanical ventilation more often (11 (48%) vs 7 (18%), multivariable OR 3.11 (95% CI 1.07 to 9.05)). Mortality was similar between the two groups (3 (6%) vs 4 (4%), p=0.69). CONCLUSIONS: Patients with rheumatic disease and COVID-19 infection were more likely to require mechanical ventilation but had similar clinical features and hospitalisation rates as those without rheumatic disease. These findings have important implications for patients with rheumatic disease but require further validation.

Improved survival with renal transplantation for end-stage renal disease due to granulomatosis with polyangiitis: data from the United States Renal Data System.

BACKGROUND: Renal transplantation is the optimal treatment for selected patients with end-stage renal disease (ESRD). However, the survival benefit of renal transplantation among patients with ESRD attributed to granulomatosis with polyangiitis (GPA) is unknown. METHODS: We identified patients from the United States Renal Data System with ESRD due to GPA (ESRD-GPA) between 1995 and 2014. We restricted our analysis to waitlisted subjects to evaluate the impact of transplantation on mortality. We followed patients until death or the end of follow-up. We compared the relative risk (RR) of all-cause and cause-specific mortality in patients who received a transplant versus non-transplanted patients using a pooled logistic regression model with transplantation as a time-varying exposure. RESULTS: During the study period, 1525 patients were waitlisted and 946 received a renal transplant. Receiving a renal transplant was associated with a 70% reduction in the risk of all-cause mortality in multivariable-adjusted analyses (RR=0.30, 95% CI 0.25 to 0.37), largely attributed to a 90% reduction in the risk of death due to cardiovascular disease (CVD) (RR=0.10, 95% 0.06-0.16). DISCUSSION: Renal transplantation is associated with a significant decrease in all-cause mortality among patients with ESRD attributed to GPA, largely due to a decrease in the risk of death to CVD. Prompt referral for transplantation is critical to optimise outcomes for this patient population.

Ambient Fine Particulate Matter, Outdoor Temperature, and Risk of Metabolic Syndrome.

Ambient air pollution and temperature have been linked with cardiovascular morbidity and mortality. Metabolic syndrome and its components-abdominal obesity, elevated fasting blood glucose concentration, low high-density lipoprotein cholesterol concentration, hypertension, and hypertriglyceridemia-predict cardiovascular disease, but the environmental causes are understudied. In this study, we prospectively examined the long-term associations of air pollution, defined as particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5), and temperature with the development of metabolic syndrome and its components. Using covariate-adjustment Cox proportional hazards models, we estimated associations of mean annual PM2.5 concentration and temperature with risk of incident metabolic dysfunctions between 1993 and 2011 in 587 elderly (mean = 70 (standard deviation, 7) years of age) male participants in the Normative Aging Study. A 1-µg/m3 increase in mean annual PM2.5 concentration was associated with a higher risk of developing metabolic syndrome (hazard ratio (HR) = 1.27, 95% confidence interval (CI): 1.06, 1.52), an elevated fasting blood glucose level (HR = 1.20, 95% CI: 1.03, 1.39), and hypertriglyceridemia (HR = 1.14, 95% CI: 1.00, 1.30). Our findings for metabolic syndrome and high fasting blood glucose remained significant for PM2.5 levels below the Environmental Protection Agency's health-safety limit (12 µg/m3). A 1°C increase in mean annual temperature was associated with a higher risk of developing elevated fasting blood glucose (HR = 1.33, 95% CI: 1.14, 1.56). Men living in neighborhoods with worse air quality-with higher PM2.5 levels and/or temperatures than average-showed increased risk of developing metabolic dysfunctions.

The Impact of Radiation Therapy in Patients with Systemic Sclerosis and Head and Neck Cancer.

OBJECTIVE: Systemic sclerosis (SSc) is considered a relative, or in some cases, absolute contraindication for radiation therapy for various cancers; however, radiation is the standard of care and the best option for tumor control for locally advanced head and neck (H&N) cancer. We present a case series to document postradiation outcomes in patients with SSc and H&N cancer. METHODS: Patients with SSc and H&N cancer treated with radiation were identified from the Johns Hopkins Scleroderma Center and the University of Pittsburgh Scleroderma Center research registries. Through chart review, we identified whether patients developed predetermined acute and late side effects or changes in SSc activity from radiation. We further describe therapies used to prevent and treat radiation-induced fibrosis. RESULTS: Thirteen patients with SSc who received radiation therapy for H&N cancer were included. Five-year survival was 54%. Nine patients (69%) developed local radiation-induced skin thickening, and 7 (54%) developed reduced neck range of motion. Two patients required long-term percutaneous endoscopic gastrostomy use due to radiation therapy complications. No patients required respiratory support related to radiation therapy. Regarding SSc disease activity among the patients with established SSc before radiation therapy, none experienced interstitial lung disease progression in the postradiation period. After radiation, one patient had worsening skin disease outside the radiation field; however, this patient was within the first year of SSc, when progressive skin disease is expected. Treatment strategies to prevent radiation fibrosis included pentoxifylline, amifostine, and vitamin E, while intravenous immunoglobulin (IVIG) was used to treat it. CONCLUSION: Although some patients with SSc who received radiation for H&N cancer developed localized skin thickening and reduced neck range of motion, systemic flares of SSc were uncommon. This observational study provides evidence to support the use of radiation therapy for H&N cancer in patients with SSc when radiation is the best treatment option.

Immune checkpoint inhibitor therapy in patients with cancer and pre-existing systemic sclerosis.

OBJECTIVE: Immune checkpoint inhibitor (ICI) therapies have dramatically improved outcomes in multiple cancers. ICI's mechanism of action involves immune system activation to augment anti-tumor immunity. Patients with pre-existing autoimmune diseases, such as systemic sclerosis (SSc), were excluded from initial ICI clinical trials due to concern that such immune system activation could precipitate an autoimmune disease flare or new, severe immune related adverse events (irAE). In the present study, we report our experience with ICIs in patients with pre-existing SSc. METHODS: Patients with SSc who received ICI therapy for cancer were identified from the Johns Hopkins Scleroderma Center Research Registry. Through chart review and prespecified definitions, we identified whether patients experienced worsening SSc activity or new irAEs. SSc disease activity worsening was pre-defined as an increase in modified Rodnan skin score (mRSS), new scleroderma renal crisis, progression of interstitial lung disease (ILD) on CT scan, increased Raynaud's phenomenon frequency or severity, new pulmonary hypertension, or myositis flare. IrAEs also included active inflammatory arthritis and dermatitis. RESULTS: Eight patients with SSc who received ICI therapy for cancer were included. Overall, SSc symptoms remained stable during and after ICI therapy. None of the patients with long-standing sine or limited cutaneous SSc (lcSSc) had progressive skin thickening after ICI therapy. One patient, who was early in his diffuse cutaneous SSc (dcSSc) disease course, experienced worsening skin thickening and renal crisis. Three patients (38 %) experienced a total of five irAEs (grade 2: diarrhea, mucositis and dermatitis; grade 3: pneumonitis, and grade 4: nephritis). The patient with grade 4 nephritis developed scleroderma renal crisis and immune checkpoint related nephritis simultaneously. There were no deaths due to irAEs. CONCLUSION: In this study, ICI therapy was well tolerated in patients with longstanding, sine or lcSSc. IrAE were common but generally manageable. Patients with early, active SSc may be at greater risk from ICI therapy, but more research is needed.

Telemedicine in Adult Rheumatology: In Practice and in Training.

Many rheumatology providers, including fellows-in-training, responded to the immediate need for maintaining patient access to care via telerheumatology during the COVID-19 pandemic. The rapidity of this transition did not permit an intentional approach to integrating fellow education and training into virtual patient care. Virtual patient care has since become an integrated, and perhaps, an embedded part of rheumatology practice that will likely endure beyond the COVID-19 pandemic. Thus, the development of best practices in telerheumatology, including those for fellow education and training as these new entrants prepare to enter our workforce, will benefit the entire specialty. In this work, we seek to describe current models for training learners in virtual patient care, characterize existing barriers to virtual care models, and offer strategies to integrate telerheumatology into curriculum development and training.

Lifetime Allergy Symptoms in IgG4-Related Disease: A Case-Control Study.

OBJECTIVE: The etiology of IgG4-related disease (IgG4-RD) is unknown, and there has been controversy over the significance of allergic conditions in IgG4-RD. We examined the prevalence of lifetime allergy symptoms in IgG4-RD and the association between these and IgG4-RD. METHODS: We identified IgG4-RD patients and non-IgG4-RD controls without autoimmune conditions seen at a single center. IgG4-RD patients were classified using the American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria. Allergy symptoms were ascertained by questionnaire. We assessed the association of IgG4-RD features with allergy symptoms. We compared the proportion of cases and controls with allergy symptoms using conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) after matching cases and controls 1:1 by age and sex. RESULTS: Lifetime allergy symptoms were reported by 165 (71%) of 231 IgG4-RD patients. Aeroallergen symptoms were most commonly reported (n = 135, 58%), followed by skin allergy symptoms (n = 97, 42%) and food allergy symptoms (n = 47, 20%). IgG4-RD cases with a history of allergy symptoms were more likely to have head and neck involvement (OR 2.0 [95% CI 1.1-3.6]) and peripheral eosinophilia (OR 3.3 [95% CI 1.2-9.0]) than those without allergy symptoms. The prevalence of any allergy symptoms was similar between cases and controls (OR 0.7 [95% CI 0.4-1.1]); this remained consistent after stratifying by head and neck involvement. CONCLUSION: Lifetime allergy symptoms are common in IgG4-RD but are not reported more often in IgG4-RD compared to non-IgG4-RD patients without autoimmune conditions. These findings suggest that allergies are not uniquely associated with the pathogenesis or presentation of IgG4-RD.

Association of Race and Ethnicity With COVID-19 Outcomes in Rheumatic Disease: Data From the COVID-19 Global Rheumatology Alliance Physician Registry.

OBJECTIVE: Racial/ethnic minorities experience more severe outcomes of coronavirus disease 2019 (COVID-19) in the general US population. This study was undertaken to examine the association between race/ethnicity and COVID-19 hospitalization, ventilation status, and mortality in people with rheumatic disease. METHODS: US patients with rheumatic disease and COVID-19 were entered into the COVID-19 Global Rheumatology Alliance physician registry between March 24, 2020 and August 26, 2020 were included. Race/ethnicity was defined as White, African American, Latinx, Asian, or other/mixed race. Outcome measures included hospitalization, requirement for ventilatory support, and death. Multivariable regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) adjusted for age, sex, smoking status, rheumatic disease diagnosis, comorbidities, medication use prior to infection, and rheumatic disease activity. RESULTS: A total of 1,324 patients were included, of whom 36% were hospitalized and 6% died; 26% of hospitalized patients required mechanical ventilation. In multivariable models, African American patients (OR 2.74 [95% CI 1.90-3.95]), Latinx patients (OR 1.71 [95% CI 1.18-2.49]), and Asian patients (OR 2.69 [95% CI 1.16-6.24]) had higher odds of hospitalization compared to White patients. Latinx patients also had 3-fold increased odds of requiring ventilatory support (OR 3.25 [95% CI 1.75-6.05]). No differences in mortality based on race/ethnicity were found, though power to detect associations may have been limited. CONCLUSION: Similar to findings in the general US population, racial/ethnic minorities with rheumatic disease and COVID-19 had increased odds of hospitalization and ventilatory support. These results illustrate significant health disparities related to COVID-19 in people with rheumatic diseases. The rheumatology community should proactively address the needs of patients currently experiencing inequitable health outcomes during the pandemic.

Association of Cigarette Smoking With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

Importance: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic small vessel vasculitis characterized by circulating ANCAs targeting proteinase 3 (PR3) or myeloperoxidase (MPO) and associated with excess morbidity and mortality. Myeloperoxidase-ANCA-positive AAV and PR3-ANCA-positive AAV are increasingly recognized to have differences in genetic risk, pathogenesis, and response to treatment. Risk factors for AAV, including cigarette smoking, are poorly understood. Objective: To examine the association between cigarette smoking and AAV. Design, Setting, and Participants: This case-control study included a consecutive inception cohort of 484 patients with AAV diagnosed from 2002 to 2017 compared with a cohort of sex-, race-, and age-matched controls. Eleven cases were excluded owing to discordant smoking information in the electronic health record. Controls were randomly selected from participants recruited to the Partners HealthCare Biobank between its inception in 2010 and 2018 and who completed a smoking questionnaire and were not diagnosed with AAV (n = 30 536). Exposures: Smoking status (current, former, never) and pack-years of cigarette smoking were determined from review of the electronic medical record and smoking questionnaires. Main Outcomes and Measures: Patients with AAV were individually matched with 3 randomly-selected controls based on sex, race, and age (within 2 years difference). Conditional logistic regression was performed to examine the association between cigarette smoking and AAV using odds ratios (OR) and 95% confidence intervals (CIs). Results: Overall, 473 cases were matched with 1419 controls (mean [SD] age, 59 [16] years; 281 women [59%], 396 white [84%]). Patients with AAV were more likely to be former (OR, 1.6; 95% CI, 1.3-2.0) or current smokers (OR, 2.7; 95% CI, 1.8-4.1); there was a dose-response relationship according to pack-years of exposure (P < .001). These associations were especially strong among participants with MPO-ANCA-positive disease (former smokers: OR, 1.7; 95% CI, 1.3-2.3; current smokers: OR, 3.5; 95% CI, 2.1-6.1) but not in participants with PR3-ANCA-positive AAV (former smokers: OR, 1.3; 95% CI, 0.9-2.0; current smokers: OR, 1.7; 95% CI, 0.8-3.5). After stratifying by selected demographics and disease manifestations, these associations remained strong. Conclusions and Relevance: Cigarette smoking was associated with AAV, especially MPO-ANCA-positive AAV. Further studies are needed to investigate a potential pathogenic mechanism.