Dried Blood Spot Testing Research Articles

Preliminary Results of Gau-PED Study: Prevalence of Gaucher Disease in Paediatric Patients Selected By an Appropriate Diagnostic Algorithm

BACKGROUNDGaucher disease (GD) is an autosomal recessive lysosomal storage disease characterized by the deficient activity of beta-glucocerebrosidase (GBA). GBA deficiency results in the accumulation of glucosylceramide in different organs, causing tissue damage. Typical GD features are spleno-hepatomegaly, peripheral blood cytopenias (mostly thrombocytopenia and/or anemia), growth retardation, bone involvement, gammopathies, increased risk of malignancies and, in some patients, neurological manifestations.Since symptoms are non-specific, the diagnosis can be delayed for years or missed.Enzyme replacement therapy (ERT) with recombinant β-glucocerebrosidase is safe and effective in preventing and/or reversing many clinical manifestations. However, if the diagnosis is delayed for years, major complications cannot be reversed.A useful screening method for GD is based on measuring enzyme activity on a Dried Blood Spot (DBS), while the gold standard test is still considered GBA activity in cellular homogenates.A pediatric algorithm has been proposed to promote timely diagnosis and early access to ERT (Di Rocco M et Al, Ped Blood & Cancer 2014;61:1905-09). AIMSSince pediatric patients with splenomegaly and cytopenias are usually referred to pediatric hematologists, we have designed the GAU-PED study to evaluate the prevalence of GD among children referred to the haematology paediatric units and selected according to the above mentioned diagnostic algorithm. Here, we report a preliminary analysis of GAU-PED trial at 18 months after the start of the enrolment. METHODSThe GAU-PED study involves 53 centers in the context of the AIEOP Study Group, the Italian clinical research consortium in paediatric hematology and oncology.Patients (1-18 years old) referring to the pediatric hematology and oncology units for spleno-w/wo hepatomegaly and cytopenia (thrombocytopenia and/or anaemia), where other causes of splenomegaly has been excluded, are tested for GBA activity though a DBS sample. Only patients with DBS showing a GBA activity below normal values are recalled to confirm GBA enzyme deficiency using the gold standard GBA analysis in cell omogenate. For every tested patient, clinical information are also collected. RESULTSDuring the first 18 months of accrual, a total of 47 DBS have been collected from 18 centers, after parental consent. DBS values under 5 pmol/punch(1)/h(1)were found in 19/47 patients (40%). These patients have been recalled for the conventional enzymatic test. The diagnosis of GD has been confirmed in 5/19 (26%) DBS positive patients. In all 5 patients the genetic analysis has been consistent with GD.Overall, in the tested population, the prevalence of GD is 10.6% (95% CI, 4 - 24%) equal to 5/47 enrolled patients.Three patients were females and 2 males. The mean age at diagnosis was 8.4 years (range 2 - 13 years). The median time from the initial clinical presentation and the diagnosis has been 12 months (range 6-120 months), while the mean time between the DBS test and the diagnosis has been 4.8 months (range 3 - 6 months). ERT has been started in all GD patients. The clinical characteristics of the 5 patients with GD are summarized in Table 1.CONCLUSION/SUMMARY: Our preliminary results support the use of DBS as screening test for GD in a selected population of children with splenomegaly and/or thrombocytopenia considered at increased risk for the disease. The use of an appropriate diagnostic algorithm is useful to increase awareness of GD among pediatric hematologists and to shorten the time to diagnosis. Taking in consideration the long life expectancy of pediatric GD patients, the early diagnosis will have a strong impact on health and quality of life. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Fabry Cardiomyopathy: Current Practice and Future Directions.

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the galactosidase A (GLA) gene that result in deficient galactosidase A enzyme and subsequent accumulation of glycosphingolipids throughout the body. The result is a multi-system disorder characterized by cutaneous, corneal, cardiac, renal, and neurological manifestations. Increased left ventricular wall thickness represents the predominant cardiac manifestation of FD. As the disease progresses, patients may develop arrhythmias, advanced conduction abnormalities, and heart failure. Cardiac biomarkers, point-of-care dried blood spot testing, and advanced imaging modalities including echocardiography with strain imaging and magnetic resonance imaging (MRI) with T1 mapping now allow us to detect Fabry cardiomyopathy much more effectively than in the past. While enzyme replacement therapy (ERT) has been the mainstay of treatment, several promising therapies are now in development, making early diagnosis of FD even more crucial. Ongoing initiatives involving artificial intelligence (AI)-empowered interpretation of echocardiographic images, point-of-care dried blood spot testing in the echocardiography laboratory, and widespread dissemination of point-of-care ultrasound devices to community practices to promote screening may lead to more timely diagnosis of FD. Fabry disease should no longer be considered a rare, untreatable disease, but one that can be effectively identified and treated at an early stage before the development of irreversible end-organ damage.

SporTRIA study—a multicentre trial protocol for excretion kinetics of triamcinolone acetonide following sport-related intra-articular injections in knees: definitions of the washout periods

IntroductionIntra-articular (IA) and peri-articular glucocorticoid (GC) injections are common in sports medicine. However, from 1 January 2022, all injectable GC routes (including IA administration) will be prohibited in-competition by World...

High Prevalence of Late-Onset Fabry Cardiomyopathy in a Cohort of 499 Non-Selective Patients with Left Ventricular Hypertrophy: The Asian Fabry Cardiomyopathy High-Risk Screening Study (ASIAN-FAME).

Left ventricular hypertrophy (LVH) caused by cardiac variant Fabry disease (FD) is typically late-onset and may mimic LVH caused by abnormal loading conditions. We aimed to determine the prevalence of FD in a non-selective patient population of everyday practice presenting with LVH, including those with hypertension and valve disease. We measured plasma alpha-galactosidase A activity using dried blood spot tests in 499 (age = 66 ± 13 years; 336 men) Hong Kong Chinese patients with LVH defined as maximal LV septal/posterior wall thickness ≥13 mm on echocardiography. Patients with low enzyme activity underwent mutation analysis of the GLA gene. Eight (age = 53−74 years; all men) unrelated patients (1.6%) had low plasma alpha-galactosidase A activity (0.57 ± 0.27 μmol/L wb/hr) and all were confirmed to have the GLA IVS4 + 919G > A mutation. FD patients presented with heart failure (n = 5), heart block (n = 2), ventricular tachycardia (n = 1), chest pain (n = 3), and/or murmur (n = 1). Uncontrolled hypertension (n = 4) and/or severe mitral/aortic valve pathology (n = 2) were frequent. Ethnic subgroups included Teochew (n = 5), Canton (n = 2), and Wenzhou (n = 1). Endomyocardial biopsy (n = 6) revealed hypertrophic myocytes with vacuolization and dense lamellar bodies. Late-onset IVS4 + 919G > A FD is prevalent among Chinese LVH patients, and should be considered as a cause of LVH in adult patients even when hypertension and/or valve pathology are present.

Exploration of an Efficient Simultaneous Molecular Detection Method of HIV, HCV, and Syphilis from a Single Dried Blood Spot

ObjectiveThe aim of the present study was to evaluate the performance of the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA using one dried blood spot (DBS) as an alternative sample to plasma. MethodA total of 571 paired DBS/plasma samples were collected from men who have sex with men (MSM) and injection drug users (IDUs), and serological and molecular assays were performed. Using plasma results as the reference standard, the performance of DBS tests for HIV-1 RNA, HIV-1 DNA, and HCV RNA was evaluated. Pearson's correlation coefficients and Bland-Altman analysis were performed to assess the correlation and concordance between DBS and plasma. ResultsAmong paired plasma/DBS samples with detectable HIV-1 RNA and HCV RNA, five samples (5/32) were not detectable in DBS, while measurable HIV-1 RNA levels were present in plasma (1.44 to 3.99 log10 copies/mL). There were two samples (2/94) with undetectable HCV RNA in DBS, while measurable HCV RNA levels were present in plasma (−5 to 5.99 log10 copies/mL). The correlation between HIV-1 RNA light chain variable region (VL) values obtained from plasma and DBS showed that r = 0.683 (P < 0.01), n = 27 and r = 0.612 (P < 0.01), n = 89 in HCV RNA. Bland-Altman analysis revealed that in HIV-1 RNA, the mean (± SD) difference between HIV-1 RNA in plasma and DBS was 1.00 ± 1.01 log10 copies/mL, and all samples were within ± 1.96 SD (−0.97 to 2.97 log10 copies/mL) for DBS. The mean difference (± SD) in HCV RNA was 0.15 ± 1.08 log10 copies/mL, and 94.38% (84/89) were within ± 1.96 SD (−1.96 to 2.67 log10 copies/mL). Overall, HIV-1 RNA and HCV RNA levels obtained from a DBS were lower than those obtained from plasma. HIV-1 DNA in a DBS showed concordant results with HIV-1 RNA in plasma. HIV-1 DNA RT-PCR using a DBS showed acceptable performance. ConclusionThe performance of the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA using one DBS was acceptable. DBS, as an alternative sample to plasma, may be a viable option for the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA in resource-limited settings or for individuals living in areas that are difficult to access.

Telemedicine and decentralized hepatitis C treatment as a strategy to enhance retention in care among people attending drug treatment centres.

People attending drug treatment centres have a high burden of hepatitis C virus (HCV) and face barriers to diagnosis and treatment. Dried blood spot (DBS) testing has been proposed to simplify diagnosis, but many patients remain untreated. In this retrospective study, we evaluated the reasons for non-retention in care in an intervention using on-site DBS testing and the effect of telemedicine and decentralized care compared to standard of care among people attending drug treatment centres who were lost to follow-up. In a first phase, retention in care, adherence to treatment, and predictive factors in the DBS testing program of patients in drug treatment centres were analyzed and compared to a cohort of patients treated at the hospital outpatient clinic. Subsequently, in a second phase we evaluated in patients lost to follow-up from drug treatment centres the efficacy of one-step testing and telemedicine linked to a decentralized dispensation of HCV treatment or standard of care. Among 512 patients attending drug treatment centres, 467 (91.2%) agreed to be tested and 53.4% (237 patients/444 valid tests) tested positive (46±9 years, 87.3% male) for HCV antibodies. After excluding patients negative for RNA or under surveillance, 178 patients were scheduled to meet with a specialist. Overall, 44 patients did not attend and 25 did not complete the pre-treatment evaluation. The only factor associated with retention in care was patient's knowledge of HCV infection. Treated patients attending drug treatment centres (n=68) compared to the hospital outpatient clinic cohort (n=135) had lower rates of treatment adherence. Among the patients who attended drug treatment centres that were lost to follow-up (n=69), the proportion of patients who completed the program was significantly higher among those assisted by telemedicine than by standard of care (62.5% vs. 24.3%, p=0.002). Although there was a high participation rate in a DBS testing program in drug treatment centres, non-retention in care is a challenge. Importantly, telemedicine linked to a decentralized dispensation of HCV treatment re-engages patients and may be effective for HCV microelimination.

Prevalence of SARS-CoV-2 Antibodies in a Multistate Academic Medical Center

ObjectiveTo estimate the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in health care personnel. MethodsThe Mayo Clinic Serology Screening Program was created to provide a voluntary, two-stage testing program for SARS-CoV-2 antibodies to health care personnel. The first stage used a dried blood spot screening test initiated on June 15, 2020. Those participants identified as reactive were advised to have confirmatory testing via a venipuncture. Venipuncture results through August 8, 2020, were considered. Consent and authorization for testing was required to participate in the screening program. This report, which was conducted under an institutional review board–approved protocol, only includes employees who have further authorized their records for use in research. ResultsA total of 81,113 health care personnel were eligible for the program, and of these 29,606 participated in the screening program. A total of 4284 (14.5%) of the dried blood spot test results were “reactive” and warranted confirmatory testing. Confirmatory testing was completed on 4094 (95.6%) of the screen reactive with an overall seroprevalence rate of 0.60% (95% CI, 0.52% to 0.69%). Significant variation in seroprevalence was observed by region of the country and age group. ConclusionThe seroprevalence for SARS-CoV-2 antibodies through August 8, 2020, was found to be lower than previously reported in other health care organizations. There was an observation that seroprevalence may be associated with community disease burden.

Protocol for an open-label feasibility study for a randomised controlled trial of vitamin D supplementation in Crohn\u2019s Disease patients with vitamin D deficiency: D-CODE Feasiblity study

BackgroundCrohn's disease (CD) is a principal form of inflammatory bowel disease, affecting approximately 1 in every 650 people in the UK. Vitamin D deficiency is common in approximately 57.7% of CD patients; with anaemia occurring in about 43% of patients. There is growing evidence that supplementing CD patients who are vitamin D deficient may be effective in reducing the severity of CD symptoms and reducing iron-deficiency anaemia. Nevertheless, National Institute for Health and Care Excellence guidance regarding the management of CD does not address vitamin D deficiency in these patients. The aims of the study are (1) to determine the prevalence of vitamin D deficiency in adults with CD in Birmingham, UK and (2) to assess the feasibility of conducting a multi-site randomised controlled trial in adult patients with CD and vitamin D deficiency.MethodsD-CODE consists of two parts—a screening study and an open-label randomised controlled feasibility study.Vitamin D screeningThree hundred patients, 18 years or older with CD will have a dried blood spot test to measure vitamin D levels. Dietary and sun exposure data will be collected. Eligible patients with low levels of vitamin D will be invited to participate in the feasibility study.Feasibility studyFifty participants with CD and vitamin D deficiency will be randomised to receive either a low (400 IU daily for 24 weeks) or high (3200 IU daily for 12 weeks then vitamin D3 800 IU daily for 12 weeks) dose of vitamin D3 oral supplementation.Patient-reported outcomes (Inflammatory Bowel Disease Questionnaire, EQ-5D-5L and Crohn’s Disease Activity Index Score) will be collected at weeks 0 and 24. Biochemical monitoring will take place at weeks 0, 12 and 24 and will measure 25-hydroxyvitamin D, corrected calcium, albumin, parathyroid hormone, hepcidin, other vitamin D metabolites, iron studies and C-reactive protein. Faecal calprotectin will be measured at weeks 0 and 24.DiscussionA key aspect of D-CODE is the identification of vitamin D deficiency prior to supplementation. It is hoped that this feasibility study will lead to a definitive trial that will investigate the benefits of treating vitamin D deficiency in patients with CD.Trial registrationThe trial has been registered with EudraCT number 2018-003910-42, ClinicalTrials.gov identifier NCT03718182 and ISRCTN number 15717783.

Transferrin isoform analysis from dried blood spots and serum samples by gel isoelectric focusing for screening congenital disorders of glycosylation.

Congenital disorders of glycosylation (CDG) are a growing, heterogeneous group of genetic disorders caused by a defect in the glycoprotein synthesis. The first and still widely used method for routine CDG screening was isoelectric focusing (IEF) of serum transferrin. Dried blood spot (DBS) testing is commonly used in newborn screening procedures to detect inborn errors of metabolism. The aim of this study was to demonstrate the reliability of the IEF method in DBS testing. Dried blood spot testing can help in the postmortem diagnosis of CDG disorders when other material is unavailable. The patterns and concentrations of transferrin isoforms in serum and DBS are comparable, and slight differences do not affect interpretation of results.

Screening for Gaucher Disease Using Dried Blood Spot Tests: A Japanese Multicenter, Cross-sectional Survey.

Objective For patients with Gaucher disease (GD), a rare, inherited lysosomal storage disease, obtaining a definitive diagnosis is currently time-consuming and costly. A simplified screening method to measure the glucocerebrosidase (GBA) activity using dried blood spots (DBS) on filter paper has recently been developed. Using this newly developed screening method, we evaluated real-world GD screening in patients suspected of having GD. Methods This multicenter, cross-sectional, observational study with a diagnostic intervention component evaluated real-world screening in patients suspected of having GD based on their clinical symptoms and a platelet count <120,000/μL. The endpoint was the number of patients with low GBA activity determined using DBS. Results In 994 patients who underwent initial DBS screening, 77 had low GBA activity. The assay was not repeated in 1 patient who was diagnosed as having a high possibility of GD due to clinical symptoms, and a further 21 patients completed the study without undergoing the second assay. Of the remaining 55 patients who had 2 DBS assays performed, 11 had a low GBA activity in both assays. Overall, DBS screening identified 12 (1.2%) patients with a low GBA activity, a proportion consistent with prior screening studies. Conclusion These results suggest that the simplified DBS method was less burdensome to patients, was easily utilized by many physicians, and could be a useful first-tier screening assay for GD prior to initiating burdensome genetic testing.

The performance of hepatitis C virus (HCV) antibody point-of-care tests on oral fluid or whole blood and dried blood spot testing for HCV serology and viral load among individuals at higher risk for HCV in South Africa.

Background and AimsTo enhance screening and diagnosis in those at‐risk of hepatitis C virus (HCV), efficient and improved sampling and testing is required. We investigated the performance of point‐of‐care (POC) tests and dried blood spots (DBS) for HCV antibody and HCV RNA quantification in individuals at higher risk for HCV (people who use and inject drugs, sex workers and men who have sex with men) in seven South African cities.MethodsSamples were screened on the OraQuick HCV POC test (471 whole blood and 218 oral fluid); 218 whole blood and DBS paired samples were evaluated on the ARCHITECT HCV antibody (Abbott) and HCV viral load (COBAS Ampliprep/COBAS TaqMan version 2) assays. For HCV RNA quantification, 107 dB were analyzed with and without normalization coefficients.ResultsPOC on either whole blood or oral fluid showed an overall sensitivity of 98.5% (95% CI 97.4‐99.5), specificity of 98.2% (95% CI 98.8‐100) and accuracy of 98.4% (95% CI 96.5‐99.3). On the antibody immunoassay, DBS showed a sensitivity of 96.0% (95% CI 93.4‐98.6), specificity of 97% (95% CI 94.8‐99.3) and accuracy of 96.3% (95% CI 93.8‐98.8). A strong correlation (R 2 = 0.90) between viral load measurements for DBS and plasma samples was observed. After normalization, DBS viral load results showed an improved bias from 0.5 to 0.16 log10 IU/mL.ConclusionThe POC test performed sufficiently well to be used for HCV screening in at‐risk populations. DBS for diagnosis and quantification was accurate and should be considered as an alternative sample to test. POC and DBS can help scale up hepatitis services in the country, in light of our elimination goals.

Sensitivity of Dried Blood Spot Testing for Detection of Congenital Cytomegalovirus Infection

The sensitivity of dried blood spots (DBS) to identify newborns with congenital cytomegalovirus (cCMV) infection has not been evaluated in screening studies using the current, higher-sensitivity methods for DBS processing. To assess the sensitivity of DBS polymerase chain reaction (PCR) for newborn screening for cCMV infection using saliva as the reference standard for screening, followed by collection of a urine sample for confirmation of congenital infection. This population-based cohort study took place at 5 newborn nurseries and 3 neonatal intensive care units in the Minneapolis/Saint Paul area in Minnesota from April 2016 to June 2019. Newborns enrolled with parental consent were screened for cCMV using DBS obtained for routine newborn screening and saliva collected 1 to 2 days after birth. Dried blood spots were tested for CMV DNA by PCR at both the University of Minnesota (UMN) and the US Centers for Disease Control and Prevention (CDC). Saliva swabs were tested by CMV DNA PCR at the UMN laboratory only. Newborns who screened positive by saliva or DBS had a diagnostic urine sample obtained by primary care professionals, tested by PCR within 3 weeks of birth. Analysis began July 2019. Detection of CMV from a saliva swab using a PCR assay. Number of children with urine-confirmed cCMV and the proportion of them who were CMV positive through DBS screening. Of 12 554 individuals enrolled through June 2019 (of 25 000 projected enrollment), 56 newborns were confirmed to have cCMV (4.5 per 1000 [95% CI, 3.3-5.7]). Combined DBS results from either UMN or CDC had a sensitivity of 85.7% (48 of 56; 95% CI, 74.3%-92.6%), specificity of 100.0% (95% CI, 100.0%-100.0%), positive predictive value (PPV) of 98.0% (95% CI, 89.3%-99.6%), and negative predictive value (NPV) of 99.9% (95% CI, 99.9%-100.0%). Dried blood spot results from UMN had a sensitivity of 73.2% (95% CI, 60.4%-83.0%), specificity of 100.0% (100.0%-100.0%), PPV of 100.0% (95% CI, 91.4%-100.0%), and NPV of 99.9% (95% CI, 99.8%-99.9%). Dried blood spot results from CDC had a sensitivity of 76.8% (95% CI, 64.2%-85.9%), specificity of 100.0% (95% CI, 100.0%-100.0%), PPV of 97.7% (95% CI, 88.2%-99.6%), and NPV of 99.9% (95% CI, 99.8%-99.9%). Saliva swab results had a sensitivity of 92.9% (52 of 56; 95% CI, 83.0%-97.2%), specificity of 99.9% (95% CI, 99.9%-100.0%), PPV of 86.7% (95% CI, 75.8%-93.1%), and NPV of 100.0% (95% CI, 99.9%-100.0%). This study demonstrates relatively high analytical sensitivity for DBS compared with previous studies that performed population-based screening. As more sensitive DNA extraction and PCR methods continue to emerge, DBS-based testing should remain under investigation as a potential low-cost, high-throughput option for cCMV screening.

Hepatitis C reflex testing in Spain in 2019: A story of success

BackgroundReflex testing is necessary to achieve the objectives of hepatitis C elimination. However, in 2017 only 31% of Spanish hospitals performed reflex test. As a consequence of that finding, reflex testing was recommended by scientific societies involved in the diagnosis and treatment of hepatitis C. ObjectiveTo evaluate the degree of implementation of reflex testing in 2019 and to know the implementation of rapid diagnostic and/or dried blood spot testing (RDT and / or DBS) in Spanish hospitals. MethodsCross-sectional study through a survey conducted in October 2019 to Spanish general hospitals with at least 200 beds, public or private with teaching accreditation. Results129 (80%) hospitals responded. Reflex testing is performed by 89% of the centres vs. 31% in 2017 (P<.001). From 2017 to 2019, centres using alerts to improve continuity of care increased from 69% to 86% (P=.002). In 2019, 11% of centres can determine anti-HCV in dried spot, 15% viremia in dried spot, 0.85% anti-HCV in saliva, and 37% of antibodies and/or viremia with point of care test. 43% of hospitals have at least one diagnostic method with RDT and/or DBS. ConclusionThe implementation of reflex testing has increased significantly, reaching 89% of hospitals in 2019. The recommendations of scientific societies could have contributed to the implementation of reflex testing. On the other hand, access to RDT and/or DBS is insufficient and initiatives are needed to improve their implementation.

Adapting to telemedicine in the COVID-19 era: Feasibility of dried blood spot testing for hemoglobin A1c

Background and aimsThe COVID-19 pandemic has led to a rapid growth in the use of telemedicine for delivery of ambulatory diabetes care. This study evaluated the feasibility of remote HbA1c monitoring via dried blood spot (DBS) testing to support assessment of glycemic control for telemedicine visits and examined clinical and demographic characteristics associated with patient completion of DBS testing. MethodsProviders could place orders for DBS HbA1c 3 weeks prior to telemedicine visits. Feasibility was assessed by examining DBS completion rates, time to completion, and availability of DBS results prior to telemedicine visits. Chi-square tests and Mann Whitney tests were used to assess whether completion rates were associated with participant characteristics. ResultsOf 303 DBS orders placed for telemedicine visits in June 2020, 162 patients completed the DBS test for a completion rate of (53.4%). Average time from collection at home to result being reported was 6.9 (3.8) days. The DBS result was available in 67.6% of patients who completed successful DBS, before the telemedicine clinic visit. HbA1c was lower in the DBS completion group as compared to the non-completion group (8.2% vs. 8.9%, p = 0.01). No other clinical or demographic characteristics were significantly different between the two groups. ConclusionRemote HbA1c monitoring via DBS is feasible and offers an avenue to support assessment of glycemic control for patients seen via telemedicine. Future work should focus on improving clinic and laboratory processes to support remote DBS collection.

Rana dijagnoza neuronske* ceroidne lipofuscinoze tip 2 - mit ili stvarnost?

Neuronal ceroid lipofuscinosis type 2 (CLN2) is the most common childhood progressive neurodegenerative disease. The main features of CLN2 disease are language delay that precedes epileptic seizures, motor disorders, progressive deterioration of vision and cognition with death in early adolescence. The average time from the onset of fi rst symptoms to diagnosis is about two years. Delay in diagnosis postpones therapeutic approach involving multidisciplinary health care and effi cacious enzyme replacement therapy with cerliponase alpha (Brineura®). The availability of enzyme replacement therapy classifi es CLN2 disease in the group of treatable neurodegenerative diseases. Recognition of early symptoms is crucial to direct clinicians to appropriate examinations or seek additional expert opinion. Timely diagnosis is imperative because it allows treatment at an early stage of the disease. In all children with the fi rst unprovoked epileptic seizures between the ages of two and four, and particularly in those children with a history of language delay and motor impairment, the fi rst step is to measure the TTP1 enzyme activity by dried blood spot testing, which is available in our setting. Genetic testing and a fi nding of pathogenic mutations in the CLN2 gene confi rm the diagnosis. Raising awareness of CLN2 disease as a treatable and potentially curable disease and following the proposed guidelines will certainly contribute to early diagnosis of CLN2 disease to become our reality rather than a myth. Timely and accurate diagnosis is the fi rst step in improving the overall care of children with CLN2 disease and their parents.

Evaluation of Circulating Cardiovascular Biomarker Levels for Early Detection of Congenital Heart Disease in Newborns in Sweden

Congenital heart disease (CHD) is the most common congenital malformation in humans worldwide. Circulating cardiovascular biomarkers could potentially improve the early detection of CHD, even in asymptomatic newborns. To assess the performance of a dried blood spot (DBS) test to measure the cardiovascular biomarker amino terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP) levels in newborns and to compare DBS with standard EDTA analysis in control newborns during the first week of life. This diagnostic study was conducted in a single regional pediatric service in southern Sweden. Healthy, term neonates born between July 1, 2018, and May 31, 2019, were prospectively enrolled and compared against retrospectively identified newborns with CHD born between September 1, 2003, and September 30, 2019. Neonates who required inpatient treatment beyond the standard postnatal care were excluded. New DBS test for NT-proBNP quantification in newborns that used 3 μL of blood vs the current screening standard. Performance of the new test and when combined with pulse oximetry screening was measured by receiver operating characteristic curve analysis. Performance of the new test and EDTA screening was compared using Pearson linear correlation analysis. The DBS samples of 115 neonates (81 control newborns and 34 newborns with CHD, of whom 63 were boys [55%] and the mean [SD] gestational age was 39.6 [1.4] weeks) were analyzed. The new NT-proBNP test alone identified 71% (n = 24 of 34) of all CHD cases and 68% (n = 13 of 19) of critical CHD cases as soon as 2 days after birth. Detection of any CHD type improved to 82% (n = 28 of 34 newborns) and detection of critical CHD improved to 89% (n = 17 of 19 newborns) when combined pulse oximetry screening and NT-proBNP test results were used. Performance of the NT-proBNP test was excellent when control newborns were matched to newborns with CHD born between July 1, 2018, and May 31, 2019 (area under the curve, 0.96; SE, 0.027; 95% CI, 0.908-1.0; asymptotic P < .05). This study found that NT-proBNP assay using minimal DBS samples appears to be timely and accurate in detecting CHD in newborns and to discriminate well between healthy newborns and newborns with various types of CHD. This finding warrants further studies in larger cohorts and highlights the potential of NT-proBNP to improve neonatal CHD screening.

Field evaluation of HIV-1 viral load monitoring in adults and children receiving antiretroviral treatment in Nigeria by dried blood spot testing with RealTime HIV-1 on m2000.

In resource-limited settings, use of dried blood spots (DBS) could be a pragmatic alternative to plasma for VL monitoring in people living with HIV (PLWH). We compared results from DBS to standard plasma VL testing under field conditions in patients receiving antiretroviral therapy (ART). DBS cards were prepared from venous blood (V-DBS), finger-pricks using micro-capillary tubes (M-DBS), and direct spotting (D-DBS). DBS and matched EDTA plasma were tested on the Abbott m2000 platform using the appropriate RealTime HIV-1 quantitative CE protocol. Matched plasma samples were also tested on the Roche COBAS Ampliprep/COBAS TaqMan version 2.0. Diagnostic accuracy indicators (sensitivity, specificity, misclassification rate, and kappa coefficient) for viral failure (VF) based on different VL threshold levels and agreement of absolute VL were calculated. A total of 669 participants provided 2676 samples. V-DBS had a peak sensitivity for VF of 89.1 % [95 % CI: 85.5-92.7] at the 1000 copies/mL threshold and a peak specificity of 97.4 % [95 % CI: 95.9-99.0] at the 5000 copies/mL threshold. The lowest proportion of upward misclassification (patients classified with VF who actually had viral suppression) for V-DBS was 3.1 % [95 % CI: 1.4-4.8] at the 5000 copies/mL threshold, whereas the lowest proportion of downward misclassification (patients classified as undetectable who actually had VF) was 10.9 % [95 % CI: 7.2-14.5] at the 1000 copies/mL threshold. Abbott RealTime HIV-1 VL results from all 3 DBS types for adults and children showed strong correlation with the gold standard plasma-based assay. DBS could be useful for monitoring VL in resource limited settings such as Nigeria.

Abstract 13424: Demographic and Echocardiographic Predictors of Later-onset Cardiac Variant of Fabry Disease Among Chinese Patients With Left Ventricular Hypertrophy

Introduction: The genetic mutation IVS4+919G&gt;A commonly found among Chinese is associated with later-onset cardiac variant of Fabry disease (FD). Patients with left ventricular hypertrophy (LVH) may be screened for FD by measuring plasma α-galactosidase activity. Objective: The aim of our study is to determine the prevalence of FD among Chinese LVH patients and to define demographic and echocardiographic predictors of FD. Methods: We measured plasma α-galactosidase activity using dried blood spot test in 500 Hong Kong Chinese patients with LVH (defined as maximal left ventricular septal or posterior wall thickness ≥13 mm on transthoracic echocardiography). LVH and deficiency in α-galactosidase activity prompted genetic analysis of galactosidase alpha gene. Demographic and echocardiographic predictors of FD were analysed. Results: There are 9 (1.8%) of 500 LVH patients (all men, age 53–74 years) had low α-galactosidase activity (0.64±0.32 μmol/L wb/hr) and all were confirmed to have the FD genotype IVS4+919G&gt;A. Among these 9 FD patients, 6 (66.7%) could be traced to the ancestral home Chaozhou (southern part of China), 4 had hypertension, but none exhibited extracardiac manifestations of FD. The left ventricular mass of FD patients ranged from 64.91–811.81 g. Ancestral home Chaozhou (odds ratio, 10.28; 95% confidence Interval, 2.52–41.94; p=0.001) and LVM ≥290 g (odds ratio, 7.39; 95% confidence Interval, 1.94–28.20; p=0.003) were predictors of FD. On receiver operating characteristic curve analysis, sensitivity and specificity of LVM ≥290 g to diagnose FD vs non-FD LVH are 67% and 86.4% respectively (area under curve, 0.8; p=0.002). Conclusion: There is a high prevalence of later-onset cardiac variant FD among Hong Kong Chinese LVH patients that is associated with IVS4+919G&gt;A genotype. Male patients with ancestral home Chaozhou and LVM ≥290 g are at an increased risk of FD among Chinese LVH patients and should be screened with dried blood spot test.

Feasibility and acceptability of implementing early infant diagnosis of HIV in Papua New Guinea at the point of care: a qualitative exploration of health worker and key informant perspectives

IntroductionEarly infant diagnosis (EID) of HIV and timely initiation of antiretroviral therapy can significantly reduce morbidity and mortality among HIV-positive infants. Access to EID is limited in many low-income and...

Laboratory-based dried blood spot testing for hepatitis C: A protocol for systematic review and meta-analysis of diagnostic accuracy.

Background: Diagnosis of chronic hepatitis C virus (HCV) infection typically involves collection of venous blood samples prior to serological investigation of an antibody response followed by a confirmatory viral load or antigen test to verify active HCV infection. This conventional pathway poses logistical challenges for the implementation of reflex testing, whereby the confirmatory test is performed on the same sample used for serological investigation. Dried blood spot (DBS) testing, in which capillary blood is deposited on filter paper, is a less invasive alternative that can enable reflex testing without the need for venepuncture, centrifugation and freezing of samples. Methods: This systematic review aims to assess the diagnostic accuracy of DBS compared with venous blood samples for diagnosis of chronic HCV infection. Observational studies which compare diagnostic tests using DBS with those using serum, plasma or whole blood in patients with chronic or resolved HCV infection will be included. Electronic searches will be conducted in PubMed, Embase, Scopus, Web of Science, Lilacs and the Cochrane library. Citation screening, data extraction and quality appraisal of included studies will be performed in duplicate using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A meta-analysis will be conducted to derive pooled estimates of sensitivity, specificity, positive likelihood ratios, negative likelihood ratios, and diagnostic odds ratios. Sensitivity analyses and meta-regression will also be performed. Quality of the evidence will be evaluated using the GRADE criteria. Discussion: Identifying and linking people with currently undiagnosed chronic HCV infection to care is pivotal to attaining global viral hepatitis elimination targets. The use of DBS could simplify diagnostic testing strategies by integrating reflex testing into the care pathway and reducing drop-off along the cascade of care. Registration: PROSPERO, CRD42020205204. Registered 19 th September 2020.