Guidelines for the retention, storage, and use of residual dried blood spot samples after newborn screening analysis: statement of the Council of Regional Networks for Genetic Services

Assessing interstate racial and socioeconomic disparities in newborn screening policies in the United States

Introduction

This paper explores racial and socioeconomic disparities in newborn screening (NBS) policies across the United States. While inter-state inequality in healthcare policies is often considered a meaningful source of systemic inequity in healthcare outcomes, to the best of our knowledge, no research has explored racial and socioeconomic disparities in newborn screening policies based on state of residence.

Methods

We investigate these disparities by calculating weighted average exposure to specific NBS tests by racial and socioeconomic group. We additionally estimate count models of the number (and type) of NBS conditions screened for by state racial and socioeconomic composition.

Results

Adding to the knowledge base that social determinants of health and health disparities are linked, our analysis surprisingly reveals little evidence of substantial inter-state inequity in newborn screenings along racial and socioeconomic lines.

Discussion

While there is substantial nationwide racial and socioeconomic inequity in terms of infant health, the distribution of state-level policies does not appear to be structured in a manner to be a driver of these disparities. Our findings suggest that efforts to reduce inequities in outcomes related to NBS should shift focus toward the delivery of screening results and follow-up care as discussion builds on expanding NBS to include more conditions and genomic testing.

Harmonization of distributed multi-center analysis based on dried blood spot reference materials supporting the screening of neonatal inherited metabolic disorders

BACKGROUND

The standardization of quantification data is critical for ensuring the reliability and measurement traceability in the screening of neonatal inherited metabolic disorders. However, the availability of national certified reference materials is limited in China.

METHODS

In this study, we developed a series of dried blood spot (DBS) reference materials containing 9 amino acids (AA) and 10 acylcarnitines (AC) for neonatal screening. Four levels of the reference materials were measured with tandem mass spectrometry (MS/MS) by seven laboratories using different commercial In Vitro Diagnostic Device (IVD) kits. Then, 100 clinical samples were measured using both derivatization and non-derivatization methods by the same laboratory.

RESULTS

We found high homogeneity and stability at all levels of the reference materials, with the coefficient of variation (CV) of the analytes less than 15%. These reference materials can be used to assess the testing capabilities of different laboratories. Our test also revealed that the correction factors (CF) calculated by the reference materials, along with clinical samples, could increase the consistency for different kits.

CONCLUSION

The DBS reference materials proposed in this study provide reliability for the harmonization in multi-center analysis for the screening of neonatal inherited metabolic disorders. And applying our correction method for the screening could improve the data consistency of the DBS samples prepared by different methods.

Evaluation of the GSP Creatine Kinase-MM Assay and Assessment of CK-MM Stability in Newborn, Patient, and Contrived Dried Blood Spots for Newborn Screening for Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is a fatal X-linked disorder with a birth prevalence of 19.8:100,000 males worldwide. Elevated concentration of the muscle enzyme creatine kinase-MM (CK-MM) allows for presymptomatic screening of newborns using Dried Blood Spots (DBS). We evaluated imprecision and carryover of the FDA-approved PerkinElmer GSP Neonatal CK-MM kit over multiple runs, days, and operators, followed by quantification of CK-MM loss in stored newborn, contrived, and non-newborn patient DBS resulting from exposure to ambient versus low humidity (50-day trial), and high humidity and high temperature (8-day trial). Imprecision %CV was ≤14% for all verification comparisons and over 6 months of testing. On average, the mean CK-MM recovery after 50 days was >80% of initial concentration for all sample types stored in low humidity and <80% in ambient humidity. After 8 days of storage in high humidity and high temperature, the mean recovery for newborn samples was <80%. Verification results for the GSP Neonatal CK-MM assay were concordant with kit parameters and the assay performed consistently over 6 months. CK-MM degradation in ambient storage can be mitigated by reducing exposure to humidity. Assessment of DBS shipping and storage conditions is recommended prior to implementing DMD screening.

The use of dried blood spots for characterizing children's exposure to organic environmental chemicals

Biomonitoring is a commonly used tool for exposure assessment of organic environmental chemicals with urine and blood samples being the most commonly used matrices. However, for children's studies, blood samples are often difficult to obtain. Dried blood spots (DBS) represent a potential matrix for blood collection in children that may be used for biomonitoring. DBS are typically collected at birth to screen for several congenital disorders and diseases; many of the states that are required to collect DBS archive these spots for years. If the archived DBS can be accessed by environmental health researchers, they potentially could be analyzed to retrospectively assess exposure in these children. Furthermore, DBS can be collected prospectively in the field from children ranging in age from newborn to school-aged with little concern from parents and minimal risk to the child. Here, we review studies that have evaluated the measurement of organic environmental toxicants in both archived and prospectively collected DBS, and where available, the validation procedures that have been performed to ensure these measurements are comparable to traditional biomonitoring measurements. Among studies thus far, the amount of validation has varied considerably with no studies systematically evaluating all parameters from field collection, shipping and storage contamination and stability to laboratory analysis feasibility. These validation studies are requisite to ensure reliability of the measurement and comparability to more traditional matrices. Thus, we offer some recommendations for validation studies and other considerations before DBS should be adopted as a routine matrix for biomonitoring.

Exposure to Persistent Organic Pollutants and Birth Characteristics: The Upstate KIDS Study

BACKGROUND

Prenatal exposure to persistent organic pollutants (POPs) may be associated with obesogenic effects in offspring. Our study is the first to investigate associations between concentrations of POPs from newborn dried blood spots (DBS) and birth characteristics.

METHODS

Concentrations of 10 polychlorinated biphenyl congeners (PCBs), polybrominated diphenyl ether-47 (PBDE-47), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) were measured from DBSs collected at birth from 2,065 singleton infants. DBS samples were pooled in groups of five and assayed together to reach limits of detection. Differences in risk of large for gestational age (LGA, defined as >90th percentile of birth weight for sex and gestational age), small for gestational age (SGA, <10th), and preterm birth (gestational age <37 weeks) were estimated using logistic regression per unit (ng/ml) increase in concentration of each chemical, adjusting for individual-level covariates, including maternal age, race/ethnicity, prepregnancy BMI, education, parity, smoking, and infant sex while assuming a gamma distribution and using multiple imputation to account for pools.

RESULTS

There were 215 (11.3%) singletons born LGA, 158 (7.5%) born SGA, and 157 (7.6%) born preterm. Higher concentrations of POPs were positively associated with slightly higher risk of LGA and higher birth weight.

CONCLUSIONS

Relationships between POPs measured in newborn DBS and birth size were mixed. Pooled analysis methods using DBS could address challenges in limits of detection and costs for population-based research.

Metabolic profiles derived from residual blood spot samples: A longitudinal analysis

Background: Secondary use of newborn screening dried blood spot samples include use for biomedical or epidemiological research. However, the effects of storage conditions on archival samples requires further examination. The objective of this study was to determine the utility of residual newborn samples for deriving reliable metabolic gestational age estimates. Methods: Residual newborn dried blood spot samples that had been stored for 2-, 4-, 6-, or 12-months in temperature controlled (21°C) conditions were re-analyzed for the full panel of newborn screening analytes offered by a provincial newborn screening lab in Ottawa, Canada. Data from re-analyzed samples were compared to corresponding baseline newborn screening values for absolute agreement, and Pearson and intraclass correlation. Performance of a gestational age estimation algorithm originally developed from baseline newborn screening values was then validated on data derived from stored samples. Results: A total of 307 samples were used for this study. 17-hydroxyprogesterone and newborn hemoglobin profiles measured by immunoassay and high-performance liquid chromatography, respectively, were among the most stable markers across all time points of analysis. Acylcarnitines exhibited the greatest degree of variation in stability upon repeat measurement. The largest shifts in newborn analyte profiles and the poorest performance of metabolic gestational age algorithms were observed when samples were analyzed 12-months after sample collection. Conclusions: Duration of sample storage, independent of temperature and humidity, affects newborn screening profiles and gestational age estimates derived from metabolic gestational dating algorithms. When considering use of dried blood spot samples either for clinical or research purposes, care should be taken when interpreting data stemming from secondary use.

A critique of the regulation of data science in healthcare research in the European Union

The EU offers a suitable milieu for the comparison and harmonisation of healthcare across different languages, cultures, and jurisdictions (albeit with a supranational legal framework), which could provide improvements in healthcare standards across the bloc. There are specific ethico-legal issues with the use of data in healthcare research that mandate a different approach from other forms of research. The use of healthcare data over a long period of time is similar to the use of tissue in biobanks. There is a low risk to subjects but it is impossible to gain specific informed consent given the future possibilities for research. Large amounts of data on a subject present a finite risk of re-identification. Consequently, there is a balancing act between this risk and retaining sufficient utility of the data. Anonymising methods need to take into account the circumstances of data sharing to enable an appropriate balance in all cases. There are ethical and policy advantages to exceeding the legal requirements and thereby securing the social licence for research. This process would require the examination and comparison of data protection laws across the trading bloc to produce an ethico-legal framework compatible with the requirements of all member states. Seven EU jurisdictions are given consideration in this critique.

Comparing identified and statistically significant lipids and polar metabolites in 15-year old serum and dried blood spot samples for longitudinal studies

RATIONALE

The use of dried blood spots (DBS) has many advantages over traditional plasma and serum samples such as the smaller blood volume required, storage at room temperature, and ability to sample in remote locations. However, understanding the robustness of different analytes in DBS samples is essential, especially in older samples collected for longitudinal studies.

METHODS

Here we analyzed the stability of polar metabolites and lipids in DBS samples collected in 2000-2001 and stored at room temperature. The identified and statistically significant molecules were then compared to matched serum samples stored at -80°C to determine if the DBS samples could be effectively used in a longitudinal study following metabolic disease.

RESULTS

A total of 400 polar metabolites and lipids were identified in the serum and DBS samples using gas chromatograph/mass spectrometry (GC/MS), liquid chromatography (LC)/MS, and LC/ion mobility spectrometry-MS (LC/IMS-MS). The identified polar metabolites overlapped well between the sample types, though only one statistically significant metabolite was conserved in a case-control study of older diabetic males with low amounts of high-density lipoproteins and high body mass indices, triacylglycerides and glucose levels when compared to non-diabetic patients with normal levels, indicating that degradation in the DBS samples affects polar metabolite quantitation. Differences in the lipid identifications indicated that some oxidation occurs in the DBS samples. However, 36 statistically significant lipids correlated in both sample types.

CONCLUSIONS

The difference in the number of statistically significant polar metabolites and lipids indicated that the lipids did not degrade to as great of a degree as the polar metabolites in the DBS samples and lipid quantitation was still possible. Copyright © 2016 John Wiley & Sons, Ltd.

Evaluation of Amount of Blood in Dry Blood Spots: Ring-Disk Electrode Conductometry

A fixed area punch in dried blood spot (DBS) analysis is assumed to contain a fixed amount of blood, but the amount actually depends on a number of factors. The presently preferred approach is to normalize the measurement with respect to the sodium level, measured by atomic spectrometry. Instead of sodium levels, we propose electrical conductivity of the extract as an equivalent nondestructive measure. A dip-type small diameter ring-disk electrode (RDE) is ideal for very small volumes. However, the conductance (G) measured by an RDE depends on the depth (D) of the liquid below the probe. There is no established way of computing the specific conductance (σ) of the solution from G. Using a COMSOL Multiphysics model, we were able to obtain excellent agreement between the measured and the model predicted conductance as a function of D. Using simulations over a large range of dimensions, we provide a spreadsheet-based calculator where the RDE dimensions are the input parameters and the procedure determines the 99% of the infinite depth conductance (G99) and the depth D99 at which this is reached. For typical small diameter probes (outer electrode diameter ∼ <2 mm), D99 is small enough for dip-type measurements in extract volumes of ∼100 μL. We demonstrate the use of such probes with DBS extracts. In a small group of 12 volunteers (age 20-66), the specific conductance of 100 μL aqueous extracts of 2 μL of spotted blood showed a variance of 17.9%. For a given subject, methanol extracts of DBS spots nominally containing 8 and 4 μL of blood differed by a factor of 1.8-1.9 in the chromatographically determined values of sulfate and chloride (a minor and major constituent, respectively). The values normalized with respect to the conductance of the extracts differed by ∼1%. For serum associated analytes, normalization of the analyte value by the extract conductance can thus greatly reduce errors from variations in the spotted blood volume/unit area.

The use of mass spectrometry to analyze dried blood spots

Dried blood spots (DBS) typically consist in the deposition of small volumes of capillary blood onto dedicated paper cards. Comparatively to whole blood or plasma samples, their benefits rely in the fact that sample collection is easier and that logistic aspects related to sample storage and shipment can be relatively limited, respectively, without the need of a refrigerator or dry ice. Originally, this approach has been developed in the sixties to support the analysis of phenylalanine for the detection of phenylketonuria in newborns using bacterial inhibition test. In the nineties tandem mass spectrometry was established as the detection technique for phenylalanine and tyrosine. DBS became rapidly recognized for their clinical value: they were widely implemented in pediatric settings with mass spectrometric detection, and were closely associated to the debut of newborn screening (NBS) programs, as a part of public health policies. Since then, sample collection on paper cards has been explored with various analytical techniques in other areas more or less successfully regarding large-scale applications. Moreover, in the last 5 years a regain of interest for DBS was observed and originated from the bioanalytical community to support drug development (e.g., PK studies) or therapeutic drug monitoring mainly. Those recent applications were essentially driven by improved sensitivity of triple quadrupole mass spectrometers. This review presents an overall view of all instrumental and methodological developments for DBS analysis with mass spectrometric detection, with and without separation techniques. A general introduction to DBS will describe their advantages and historical aspects of their emergence. A second section will focus on blood collection, with a strong emphasis on specific parameters that can impact quantitative analysis, including chromatographic effects, hematocrit effects, blood effects, and analyte stability. A third part of the review is dedicated to sample preparation and will consider off-line and on-line extractions; in particular, instrumental designs that have been developed so far for DBS extraction will be detailed. Flow injection analysis and applications will be discussed in section IV. The application of surface analysis mass spectrometry (DESI, paper spray, DART, APTDCI, MALDI, LDTD-APCI, and ICP) to DBS is described in section V, while applications based on separation techniques (e.g., liquid or gas chromatography) are presented in section VI. To conclude this review, the current status of DBS analysis is summarized, and future perspectives are provided.

Validation of Biomarkers of CVD Risk from Dried Blood Spots in Community-Based Research: Methodologies and Study-Specific Serum Equivalencies

Dried blood spot (DBS) methodology offers significant advantages over venipuncture in studies of vulnerable populations or large-scale studies, including reduced participant burden and higher response rates. Uncertainty about the validity of cardiovascular disease (CVD) risk biomarkers remains a barrier to wide-scale use. We determined the validity of DBS-derived biomarkers of CVD risk versus gold-standard assessments, and study-specific, serum-equivalency values for clinical relevance of DBS-derived values. Concurrent venipuncture serum and DBS samples (n = 150 adults) were assayed in Clinical Laboratory Improvement Amendments-certified and DBS laboratories, respectively. Time controls of DBS standard samples were assayed single-blind along with test samples. Linear regression analyses evaluated DBS-to-serum equivalency values; agreement and bias were assessed via Bland-Altman plots. Linear regressions of venipuncture values on DBS-to-serum equivalencies provided R(2) values for total cholesterol, high-density lipoprotein cholesterol (HDL-C), and C-reactive protein (CRP) of 0.484, 0.118, and 0.666, respectively. Bland-Altman plots revealed minimal systematic bias between DBS-to-serum and venipuncture values; precision worsened at higher mean values of CRP. Time controls revealed little degradation or change in analyte values for HDL-C and CRP over 30 weeks. We concluded that DBS-assessed biomarkers represent a valid alternative to venipuncture assessments. Large studies using DBS should include study-specific serum-equivalency determinations to optimize individual-level sensitivity, the viability of detecting intervention effects, and generalizability in community-level primary prevention interventions.

Liquid extraction surface analysis field asymmetric waveform ion mobility spectrometry mass spectrometry for the analysis of dried blood spots

LESA mass spectrometry coupled with high field asymmetric waveform ion mobility spectrometry (FAIMS) for the analysis of dried blood spots.

Storage and use of Newborn Screening Blood Specimens for Research: Assessing Public Opinion in Illinois

Storage and use of residual dried blood spots (DBS) from newborn screening (NBS) for research purposes has been a topic of elevated interest following high profile disputes between genetic privacy advocacy groups and state NBS programs. Our objective was to assess public opinion in Illinois regarding storage and use of residual DBS for research. Five hundred twenty-six Illinois residents completed a survey assessing attitudes about research uses for DBS, storage length, and consent issues. Over 80 % of respondents expressed agreement with questions regarding research uses of DBS. Eighty-three percent of respondents were in favor of storage for at least one year with 44 % favoring indefinite storage. Respondents with higher educational attainment were more likely to support research use of DBS and less likely to desire contact for each future study (P < 0.05). Black respondents were less likely than white respondents to express agreement for the use of DBS for research or to favor long-term storage (P < 0.05). Support was high for storage and use of DBS in our sample. Consent was important and respondents wanted choices about participation. Forty-two percent of respondents were not aware of NBS prior to this survey, highlighting a need for greater education about this public health program. Trust in the public health service of NBS must be protected through transparency in the policy process.

Performance and storage integrity of dried blood spots for PCB, BFR and pesticide measurements

Dried blood spots (DBSs) can provide accurate and valuable estimates of exposure to environmental toxicants, and the use of information derived from archived newborn DBSs has enormous potential to open up new research on the impacts of early chemical exposure on disease. Broad application of DBS for the purpose of quantitative exposure estimation requires robust and validated methods. This study investigates the suitability of DBS analyses for population studies of exposure to three chemical groups: polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), and chlorinated pesticides. It examines background (matrix) contamination, recovery and extraction variability, sensitivity, and storage stability. DBS samples prepared using 50 μL of adult blood were analyzed by GC/MS, and method performance was confirmed by using certified materials and paired DBS-blood samples from six volunteers. Several of the target compounds and their degradation products have not been previously measured in DBSs. All target compounds were detected in DBS samples collected from the volunteers. Sample DBS cards showed background contamination of several compounds. When stored at room temperature, target compounds, excluding PBDEs, were stable for up to one month. When refrigerated or frozen, stability was acceptable for all compounds up to one year, and multiyear storage appears acceptable at colder (e.g., -80°C) temperatures. Multicompartment models may be used to estimate or correct for storage losses. Considering concentrations of contaminants for adults and children reported in the literature, and experimental values of detection limits and background contamination, DBS samples are suitable for quantifying exposures to many PCBs, BFRs and persistent pesticides.

Short-term stability of amino acids and acylcarnitines in the dried blood spots used to screen newborns for metabolic disorders

OBJECTIVE

Tandem mass spectrometry is increasingly used in the Middle East in newborn screening for inborn errors of metabolism using dried blood spots. The sensitivity and specificity of this system for analyzing fatty and amino acids, screening for more than 40 metabolic conditions, is known. However, the short term stability of acylcarnitines and amino acids in dried blood spots in extreme heat and humid conditions is not well documented. We examined the short term effect of heat and humidity on the levels of 7 amino acids and 10 acylcarnitines used in newborn screening for inherited metabolic disorders.

METHODS

Dried blood spots were exposed with humidity <30% to temperatures of 4, room temperature, 37° C, and 45, and also with humidity >70% at 37° C and 45. Amino acids and acylcarnitines in the dried blood spots were analyzed by tandem mass spectrometry.

RESULTS

During the eight days of the study in high temperature and high humidity storage, most acylcarnitines and amino acids lost almost 50% of initial concentration. After eight days' exposure at 37 and 45 with humidity >70%, methionine was determined to be the most sensitive, and phenylalanine and leucine were the least sensitive amino acids. At 37 with humidity >70% C6 was the most sensitive and free carnitine (C0) was the least sensitive acylcarnitine; at 45 with humidity >70% C16 was the most sensitive and C0 was the least sensitive.

CONCLUSION

Low humidity and low temperature conditions are required for transportation and storage of dried blood spots.

Ammonium improves elution of fixed dried blood spots without affecting immunofluorescence assay quality

OBJECTIVE

To solve the problem of fixed dried blood spot elution without damaging IgG antibodies.

METHODS

The minimum effective concentration of liquid ammonium (NH3 ) in a PBS solution, which was found to elute fixed blood, was determined. By using a dilution series, the effects of NH3 on IgG antibody quality were assessed using immunofluorescence assays.

RESULTS

The minimum effective concentration of 0.2% NH3 has no detectable effects on IgG quality.

CONCLUSION

Ammonium greatly improves blood elution from fixed DBS while maintaining IgG antibody quality. These results are encouraging and provide a basis for further testing of the efficacy of ammonium in different situations as well as its effect on other compounds.

Microsample analyses via DBS: challenges and opportunities

The use of DBS is an appealing approach to employing microsampling techniques for the bioanalysis of samples, as has been demonstrated for the past 50 years in the metabolic screening of metabolites and diseases. In addition to its minimally invasive sample collection procedures and its economical merits, DBS microsampling benefits from the very high sensitivity, selectivity and multianalyte capabilities of LC–MS, which has been especially well demonstrated in newborn screening applications. Only a few microliters of a biological fluid are required for analysis, which also translates to significantly reduced demands on clinical samples from patients or from animals. Recently, the pharmaceutical industry and other arenas have begun to explore the utility and practicality of DBS microsampling. This review discusses the basis for why DBS techniques are likely to be part of the future, as well as offering insights into where these benefits may be realized.

A comparative analysis of the governance and use of residual dried blood spots from state newborn screening programs and neonatal biobanks

In contrast to prior research, which has focused mainly on legislative content, this study aimed to characterize the current governance structures and procedures used by state newborn screening programs in the United States regarding the research use of residual dried blood spots. Content analysis was performed on newborn screening laws, program policies, survey responses, and online material, and was compared to information from two neonatal biobanks. Important differences between newborn screening programs and neonatal biobanks included the types of permissible research with blood spots, the evaluation criteria used for research requests, and characteristics of the research proposal reviewers. These findings can inform ongoing policy conversations with respect to the governance and use of residual dried blood spots.

A pilot study using residual newborn dried blood spots to assess the potential role of cytomegalovirus and Toxoplasma gondii in the etiology of congenital hydrocephalus

BACKGROUND

Congenital hydrocephalus is a condition characterized by accumulation of cerebrospinal fluid in the ventricles of the brain. Prenatal infections are risk factors for some birth defects. This pilot study investigated whether residual dried blood spots (DBS) could be used to assess infections as risk factors for birth defects by examining the associations between prenatal infection with Toxoplasma gondii (T. gondii) or cytomegalovirus (CMV) with congenital hydrocephalus.

METHODS

Case-infants with hydrocephalus (N=410) were identified among live-born infants using birth defects surveillance systems in California, North Carolina, and Texas. Control-infants without birth defects were randomly selected from the same geographic areas and time periods as case-infants (N=448). We tested residual DBS from case- and control-infants for T. gondii immunoglobulin M and CMV DNA. When possible, we calculated crude odds ratios (cORs) and confidence intervals (CIs).

RESULTS

Evidence for prenatal T. gondii infection was more common among case-infants (1.2%) than control-infants (0%; p=0.11), and evidence for prenatal CMV infection was higher among case-infants (1.5%) than control-infants (0.7%; cOR: 2.3; 95% CI: 0.48, 13.99).

CONCLUSIONS

Prenatal infections with T. gondii and CMV occurred more often among infants with congenital hydrocephalus than control-infants, although differences were not statistically significant. This pilot study highlighted some challenges in using DBS to examine associations between certain infections and birth defects, particularly related to reduced sensitivity and specimen storage conditions. Further study with increased numbers of specimens and higher quality specimens should be considered to understand better the contribution of these infections to the occurrence of congenital hydrocephalus.

Dried blood spot sampling for hepatitis B virus serology and molecular testing

Background & Aims

Dried blood spots (DBS) on filter paper have been successfully used to diagnose and monitor several infectious diseases. The aim was to investigate the performance of DBS in hepatitis B virus (HBV) diagnosis using commercial tests in comparison to standard methods.

Methods

Paired DBS and plasma samples were collected from 200 patients: 100 patients with HBsAg negative status and 100 patients with HBsAg positive status. In the latter patient, HBeAg reactivity was tested. Ten samples of anti-HBs were collected from people vaccinated against HBV. We also studied 50 patients with positive HBV DNA viral load in plasma and 10 HBV DNA negative patients. HBV genotypes and gene polymerase mutations were determined in 10 randomly selected HBV-infected patients. The DBS sample consisted of 50 µL of whole blood, i.e. a 12-mm paper card.

Results

The sensitivity thresholds of HBsAg and anti-HBs antibody were 0.30±0.08 IU/mL and 18.11±6.05 IU/mL, respectively, for DBS with 98% sensitivity and 100% specificity. Sensitivity was 98% and specificity 100% for the detection of HBV DNA on a blotter, considering an HBV DNA threshold of 914.1±157.8 IU/ml. Ten patients had an HBeAg positive status in plasma, all were detected positive using DBS. HBV genotyping and mutation detection were successfully performed on DBS, with full concordance between the 10 paired DBS and plasma samples.

Conclusion

This study shows DBS is a reliable alternative to plasma specimens for quantifying and detecting HBsAg, anti-HBs, HBeAg and genotyping. DBS may increase the opportunities for HBV testing and treatment follow-up in hard-to-reach individuals.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Retention and research use of residual newborn screening bloodspots

The storage and use of residual newborn screening dried blood specimens has generated significant controversy in the past 5 years, primarily because of public concerns over the lack of parental knowledge and consent for these activities. State policies addressing the management of these specimens vary widely, and there is currently little guidance to aid new state policy development to address the concerns of program professionals, investigators, and the general public. This article offers guidance for state policy based on multiple sources of data, including public attitudes, professional statements, state experience, and an analysis of the ethical, social, legal, and biomedical issues from a multidisciplinary group of scholars. This guidance will be useful for state programs that seek to develop policies that are informed by a contemporary analysis of the key ethical, legal, and social aspects of this practice. This article represents the work of the authors and does not represent American Academy of Pediatrics policy.

Lessons that newborn screening in the USA can teach us about biobanking and large-scale genetic studies

The intent in establishing newborn screening programs was not to create and sustain a large-scale genetic biobanks. Instead, newborn screening programs were designed as a public health program. As such, they have successfully screened millions of asymptomatic newborns for disease that, undiagnosed and untreated, would cause disability or death. However, historical decisions on retention of residual samples and technological innovation have forced these programs and their proponents to confront the prospect of biobanking and the conduct of large-scale genetic studies. We suggest that the challenges facing newborn screening can provide important lessons for other biobanking and large-scale genetic testing endeavors.

Governing biological material at the intersection of care and research: the use of dried blood spots for biobanking

A series of governance issues currently surrounds the multiple uses and multiple users of dried blood spots (DBS) for research purposes. Internationally there is a discussion on storing DBS resulting from newborn screening for public health and using them as the basis for large biobank-like collections to facilitate biomedical research. If such a transformation were to be formalized, then DBS would sit at the intersection of care (ie, public health) and research, with the mechanisms through which such a collection could be managed not totally self-evident. What is more, a DBS collection raises questions about the fuzzy boundaries between privacy and anonymity; how to control or define quality control uses of DBS; medical vs nonmedical uses; as well as benefit sharing and stakeholder involvement. Our goal here is to explore some of the key questions relating to DBS governance by way of the bio-objects and bio-objectification concepts. By embracing - rather than resisting to - the blurring of boundaries and problems in categorization that have come to characterize bio-objects and bio-objectification processes recently described in this journal, we attempt to highlight some issues that might not be currently considered, and to point to some possible directions to go (or avoid). Building from our knowledge of the current DBS situation in the Netherlands, we outline questions concerning the uses, management, collection, and storage of DBS.

Sensitive determination of prohibited drugs in dried blood spots (DBS) for doping controls by means of a benchtop quadrupole/Orbitrap mass spectrometer

In the present study, a new type of mass spectrometer combining a quadrupole mass filter, a higher collision dissociation (HCD) cell and an Orbitrap detector, was evaluated for the analysis of dried blood spots (DBS) in doping controls. DBS analysis is characterized by the necessity to detect prohibited compounds in sub-nanogram-per-milliliter levels with high identification capacity. After extraction of DBS with an organic solvent and liquid chromatographic separation (using a regular C18-RP-analytical UHPLC-column) of target analytes, mass spectrometry is performed with a high-resolution full scan in positive and negative mode by means of electrospray ionisation. Single-product ion mass spectra are acquired using the data-dependent analysis mode (employing an inclusion list) for previously selected precursors of known prohibited compounds with fixed retention time ranges. Besides, a sensitive screening in a targeted approach, non-targeted analysis for retrospective data evaluation is thus possible. The chosen experimental design enables the determination of various drugs from different classes with one generic sample preparation which is shown for 26 selected model compounds (Δ(9)-tetrahydrocannabinol (THC), tetrahydrocannabinol-9-carboxylic acid (THC-COOH), methylhexaneamine, methylphenidate, cocaine, nikethamide, 3,4-methylenedioxyamphetamine, N-methyl-3,4-methylenedioxyamphetamine, strychnine, mesocarb, salbutamol, formoterol, clenbuterol, metandienone, stanozolol, bisoprolol, propranolol, metoprolol, anastrazole, clomiphene, exemestane, dexamethasone, budesonide, selective androgen receptor modulator (SARM) S4 (andarine), SARM S1, hydrochlorothiazide). Generally, only qualitative result interpretation was focussed upon, but for target analytes with deuterium-labelled internal standards (salbutamol, clenbuterol, cocaine, dexamethasone, THC-COOH and THC) quantitative analysis was also possible. Especially the most challenging analytes, THC and its carboxy metabolite, were detected in DBS at relevant concentrations (<0.5 ng/mL) using targeted HCD experiments. The method was validated for the parameters: specificity, linearity (0-20 ng/mL), precision (<25%), recovery (mean 60%), limit of detection/quantification, ion suppression, stability and accuracy (80-120%). Six isotope-labelled analogues used as internal standards facilitate a quantitative result interpretation which is of utmost importance especially for in-competition drug sports testing.

Investigations into the environmental conditions experienced during ambient sample transport: impact to dried blood spot sample shipments

BACKGROUND

Prior to bioanalysis, sample transport and storage are critical considerations in any pharmacokinetic or toxicokinetic study design. Care must be taken to ensure the shipment is properly packaged and tracked to make certain it arrives at the desired, final destination in the appropriate timeframe, and that the integrity of the sample is not compromised. When dealing with biological specimens, environmental conditions may have a deleterious effect on the stability and conditions of the sample.

RESULTS

Currently, frozen plasma or blood samples are the matrix of choice within the pharmaceutical industry for analysis within both preclinical and clinical trials. Liquid samples are shipped and received frozen and, therefore, the assumption is made that the frozen conditions are maintained throughout the entire transit process. Dried blood spot and dried matrix spot samples are becoming popular alternatives to plasma sampling in many small- and even large-molecule applications. With the implementation of dried blood spot and dried matrix spot samples, shipping and storage occurs under ambient conditions.

CONCLUSION

In this article we discuss various shipping containers for these samples, illustrate the environmental extremes encountered during the shipping process, demonstrate a cost-effective method of monitoring both temperature and humidity, and discuss validation steps that may be implemented to minimize the impact of these variables on your study design.

The stability of markers in dried-blood spots for recommended newborn screening disorders in the United States

OBJECTIVE

We aimed to measure separately the contributions of heat and humidity to changes in levels of 34 markers of inborn disorders in dried-blood-spot (DBS) samples.

DESIGN AND METHODS

We stored paired sets of DBSs at 37°C for predetermined intervals in low-humidity and high-humidity environments. Marker levels of all samples in each complete sample set were measured in a single analytic run.

RESULTS

During the 30 ± 5 day studies, galactose-1-phosphate uridyltransferase and biotinidase lost almost 65% of initial activities in low-humidity storage; most of the degradation in 27 other markers was attributable to adverse effects of high-humidity storage; seven markers in DBSs stored at high humidity lost more than 90% of initial levels by the end of the study and 4 of the 7 lost more than 50% of initial levels within the first week of storage.

CONCLUSIONS

Minimizing both humidity and temperature in DBS transportation and storage environments is essential to maintaining sample integrity.

Feasibility of neonatal dried blood spot retrieval amid evolving state policies (2009-2010): a Children's Oncology Group study

Dried blood spots (DBS) are collected uniformly from US newborns to test for metabolic and other disorders. Because evidence exists for prenatal origins of some diseases, DBS may provide unique prenatal exposure records. Some states retain residual DBS and permit their use in aetiological studies. The primary study aim was to assess the feasibility of obtaining residual DBS from state newborn screening programmes for paediatric and adolescent cancer patients nationwide with parental/subject consent/assent. Families of leukaemia and lymphoma patients aged ≤21 years diagnosed from 1998 to 2007 at randomly selected Children's Oncology Group institutions across the US were questioned (n = 947). Parents/guardians and patients aged ≥18 years were asked to release DBS to investigators in spring 2009. DBS were then requested from states. Overall, 299 families (32%) released DBS. Consenting/assenting patients were born in 39 US states and 46 DBS were obtained from five states; 124 DBS were unobtainable because patients were born prior to dates of state retention. State policies are rapidly evolving and there is ongoing discussion regarding DBS storage and secondary research uses. Currently, population-based DBS studies can be conducted in a limited number of states; fortunately, many have large populations to provide reasonably sized paediatric subject groups.

Robustness of genome-wide scanning using archived dried blood spot samples as a DNA source

Background

The search to identify disease-susceptible genes requires access to biological material from numerous well-characterized subjects. Archived residual dried blood spot (DBS) samples, also known as Guthrie cards, from national newborn screening programs may provide a DNA source for entire populations. Combined with clinical information from medical registries, DBS samples could provide a rich source for productive research. However, the amounts of DNA which can be extracted from these precious samples are minute and may be prohibitive for numerous genotypings. Previously, we demonstrated that DBS DNA can be whole-genome amplified and used for reliable genetic analysis on different platforms, including genome-wide scanning arrays. However, it remains unclear whether this approach is workable on a large sample scale. We examined the robustness of using DBS samples for whole-genome amplification following genome-wide scanning, using arrays from Illumina and Affymetrix.

Results

This study is based on 4,641 DBS samples from the Danish Newborn Screening Biobank, extracted for three separate genome-wide association studies. The amount of amplified DNA was significantly (P < 0.05) affected by the year of storage and storage conditions. Nine (0.2%) DBS samples failed whole-genome amplification. A total of 4,586 (98.8%) samples met our criterion of success of a genetic call-rate above 97%. The three studies used different arrays, with mean genotyping call-rates of 99.385% (Illumina Infinium Human610-Quad), 99.722% (Illumina Infinium HD HumanOmni1-Quad), and 99.206% (Affymetrix Axiom Genome-Wide CEU). We observed a concordance rate of 99.997% in the 38 methodological replications, and 99.999% in the 27 technical replications. Handling variables such as time of storage, storage conditions and type of filter paper were shown too significantly (P < 0.05) affect the genotype call-rates in some of the arrays, although the effect was minimal.

Conclusion

Our study indicates that archived DBS samples from the Danish Newborn Screening Biobank represent a reliable resource of DNA for whole-genome amplification and subsequent genome-wide association studies. With call-rates equivalent to high quality DNA samples, our results point to new opportunities for using the neonatal biobanks available worldwide in the hunt for genetic components of disease.

State laws regarding the retention and use of residual newborn screening blood samples

BACKGROUND

After newborn screening has been completed, many states retain residual newborn screening dried blood samples for various purposes, including program evaluation, quality assurance, and biomedical research. The extent to which states possess legal authority to retain residual dried blood samples (DBS) and use them for purposes unrelated to newborn screening is unclear.

OBJECTIVE

The purpose of this study was to evaluate state laws regarding the retention and use of DBS.

METHODS

State statutes and regulations related to newborn screening of all 50 states plus the District of Columbia were accessed online between November 2008 and December 2009 and reviewed by 2 independent reviewers to determine the extent to which the retention and use of DBS were addressed.

RESULTS

The retention or use of DBS has not been addressed in 18 states. In 4 states, DBS becomes state property. Eight states require that parents be provided information regarding the retention of DBS. Parents in 5 states may request the destruction of their child's residual sample. Parental consent is required under certain circumstances to release DBS for research in 6 states. One state prohibits DBS from being used for research purposes.

CONCLUSIONS

States have wide variability in their policies regarding the retention and use of DBS. Many states have not addressed key issues, and some states that retain DBS may be acting outside the scope of their legal authority. The lack of transparency on the part of states in retaining DBS may undermine public trust in state newborn screening programs and the research enterprise.

Whole-genome amplified DNA from stored dried blood spots is reliable in high resolution melting curve and sequencing analysis

Background

The use of dried blood spots (DBS) samples in genomic workup has been limited by the relative low amounts of genomic DNA (gDNA) they contain. It remains to be proven that whole genome amplified DNA (wgaDNA) from stored DBS samples, constitutes a reliable alternative to gDNA.

We wanted to compare melting curves and sequencing results from wgaDNA derived from DBS samples with gDNA derived from whole blood.

Methods

gDNA was extracted from whole blood obtained from 10 patients with lone atrial fibrillation (mean age 22.3 years). From their newborn DBS samples, stored at -24°C, genomic DNA was extracted and whole-genome amplified in triplicates. Using high resolution melting curve analysis and direct sequencing in both wgaDNA and gDNA samples, all coding regions and adjacent intron regions of the genes SCN5A and KCNA5 were investigated.

Results

Altered melting curves was present in 85 of wgaDNA samples and 81 of gDNA samples. Sequence analysis identified a total of 31 variants in the 10 wgaDNA samples. The same 31 variants were found in the exact same pattern of samples in the gDNA group. There was no false positive or negative sequence variation in the wgaDNA group.

Conclusions

The use of DNA amplified in triplicates from DBS samples is reliable and can be used both for high resolution curve melting analysis as well as direct sequence analysis. DBS samples therefore can serve as an alternative to whole blood in sequence analysis.

Effect of specimen storage conditions on newborn dried blood spots used to assess Toxoplasma gondii immunoglobulin M (IgM)

BACKGROUND

Newborn screening programs store-under varying conditions-residual dried blood spots (DBS). Residual DBS were used to investigate the contribution of congenital infection with Toxoplasma gondii to the etiology of hydrocephalus and as a key step, we assessed the effect of storage conditions on the stability of newborn screening biomarkers.

METHODS

Infants with hydrocephalus (410 cases) were identified using population-based birth defects surveillance systems in California, North Carolina, and Texas. Infants without birth defects (448 controls) were randomly selected from the same geographic areas and time periods. California stores DBS with controlled temperature, while North Carolina and Texas store DBS under ambient conditions. After removal of personal identifiers, DBS were tested for Toxo-specific immunoglobulin-M (Toxo-IgM). Because of poor elution of DBS stored in ambient conditions, additional biomarkers were tested on a specimen subset.

RESULTS

Among 858 DBS tested, Toxo-IgM was found in 3 cases and no controls from California (N=515) and in no specimens from North Carolina or Texas (N=343). Among the 98 specimens tested for selected biomarkers, statistically significant differences were found for California vs. combined North Carolina and Texas DBS (thyroid stimulating hormone, phenylalanine, methionine, leucine and citrulline p<0.0001; tyrosine and valine p<0.001).

CONCLUSIONS

Storage conditions for residual DBS had an effect on the ability to extract, recover, and accurately measure Toxo-IgM and other biomarkers from the filter paper matrix.

Two-tier approach to the newborn screening of methylenetetrahydrofolate reductase deficiency and other remethylation disorders with tandem mass spectrometry

OBJECTIVE

To validate a 2-tier approach for newborn screening (NBS) of remethylation defects.

STUDY DESIGN

The original NBS dried blood spots of 5 patients with a proven diagnosis of a remethylation disorder and 1 patient with biochemical evidence of such disorder were analyzed retrospectively to determine disease ranges for methionine (Met; 4.7-8.1 micromol/L; 1 percentile of healthy population, 11.1 micromol/L), the methionine/phenylalanine ratio (Met/Phe; 0.09-0.16; 1 percentile of healthy population, 0.22), and total homocysteine (tHcy; 42-157 micromol/L; 99 percentile of normal population, 14.7 micromol/L). These preliminary disease ranges showed a sufficient degree of segregation from healthy population data, allowing the selection of cutoff values. A simple algorithm was then developed to reflex cases to a second-tier testing for tHcy, which has been applied prospectively for 14 months.

RESULTS

A total of 86 333 NBS samples were tested between January 2007 and March 2008, and 233 of them (0.27%) met the criteria for second-tier testing of tHcy. All cases revealed concentrations of tHcy <15 micromol/L and were considered unaffected. No false-negative results have been reported with a state-wide system based on 2 combined metabolic clinics and laboratories that cover the entire Minnesota population and border areas of neighboring states.

CONCLUSIONS

Pending more conclusive evidence from the prospective identification of additional true-positive cases, NBS for remethylation disorders appears to be feasible with existing methodologies, with only a marginal increase of the laboratory workload.

The storage and use of biological tissue samples from minors for research: a focus group study

Genetic research on pediatric stored tissue samples raises specific ethical questions that differ from those raised when adults are the donors. To investigate opinions on this matter, we conducted 10 focus group discussions. Five focus groups were conducted with adult participants and 5 had teenage participants between 15 and 19 years old. The discussions were analyzed with NVIVO 8 (qualitative research software). We found the following recurrent categories: the requirement that research should not pose any burden on children and that it should benefit other children, the trust people had in the role of parents, the need for information and the growth towards autonomy. Both the adults and teenagers we interviewed thought that the inclusion of tissue samples from minors in research had ethical implications. A major concern was that nontherapeutic research would pose no extra burden on children, which would assume the use of nonintrusive methods of gathering samples and the use of samples that were gathered in a diagnostic context. Participants, however, also understood the necessity of such research. The overall impression was that parents would be the best persons to make decisions on behalf of a small child and that the same parents would engage their children in the decision-making when they grew older. People thought that there was a duty to recontact minors when they reached the age of competence but on a best-effort basis.

Policy issues and stakeholder concerns regarding the storage and use of residual newborn dried blood samples for research

Newborn screening is an important public health programs in the United States. Over 4 million infants are screened each year for a number of conditions. There is a growing need for more explicit state policies governing the storage and research use of residual newborn samples. This paper provides an overview of newborn screening and issues related to policies of residual newborn samples as well as attitudes and opinions from stakeholders. Three groups (n = 21) were conducted with stakeholders: an African American group, a Pediatrician group and a Mothers of young children group. Despite the differences between these groups, consistent themes emerged from all groups that may be relevant for policy development governing the storage and use of residual newborn samples. The data from this exploratory study suggest that future policy developments with the newborn screening program warrant further public input on these topics.

HIV-1 and HCV detection in dried blood spots by SYBR Green multiplex real-time RT-PCR

Dried blood spot (DBS) is a reliable method of blood collection used for the diagnosis of several human diseases. DBS is particularly useful for diagnosing children and for the screening of high-risk populations especially in countries where health facilities are not readily accessible. This report describes a qualitative SYBR Green-based real-time multiplex RT-PCR for the simultaneous detection of hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) genomes in DBS. Specific viral amplicons were identified in the same sample by their distinctive melting temperatures. The analysis of scalar concentrations of the reference samples indicated that this multiplex procedure detects at least 2500 copies/ml of HCV and 400 copies/ml of HIV-1. HIV-1 and HCV viral loads in 20 patients infected with HIV-1 and/or HCV and in 5 healthy blood donors were also tested, confirming the sensitivity and specificity of the assay. This method may represent a reliable alternative for the detection of HIV-1/HCV co-infection, in rapid and relatively inexpensive screening programmes.

Genetic research on stored tissue samples from minors: a systematic review of the ethical literature

The potential benefits of biobank research are well known. Also, the ethical implications of genetic research on stored tissue samples are well discussed in existing literature. The inclusion of tissue samples from minors may have significant scientific value. However, this inclusion raises specific ethical questions. We have performed a systematic search of the literature and found 21 theoretical and empirical articles dealing with the issue. After review, we distilled five clusters of themes: consent, risks, benefits, return of results, and ownership. We have described the different components of these themes, as they occurred in the literature and have provided a discourse on the topic.

Biological sample collections from minors for genetic research: a systematic review of guidelines and position papers

Stored tissue samples are an important resource for epidemiological genetic research. Genetic research on biological material from minors can yield valuable information on the development and genesis of early-onset genetic disorders and the early interaction of environmental and genetic factors. The use of such tissue raises some specific ethical and governance questions, which are not completely covered by the discussion on biological materials from adults. We have retrieved 29 guidelines and position papers pertaining to the storage and use of biological tissue samples for genetic research, originating from 27 different organizations. Five documents have an international scope, three have an European scope and 21 have a national scope. We discovered that 11 of these documents did not contain a section on biological materials from minors. The content of the remaining 18 documents was categorized according to four themes: consent, principles of non-therapeutic research on vulnerable populations, ethics committee approval and difference between anonymous and identifiable samples. We found out that these themes are not consistently mentioned by each document, but that documents discussing the same themes were mostly in agreement with their recommendations. However, a systematic reflection on the ethical and policy issues arising from the participation of minors in biobank research is missing.

Genome-wide scans using archived neonatal dried blood spot samples

Background

Identification of disease susceptible genes requires access to DNA from numerous well-characterised subjects. Archived residual dried blood spot samples from national newborn screening programs may provide DNA from entire populations and medical registries the corresponding clinical information. The amount of DNA available in these samples is however rarely sufficient for reliable genome-wide scans, and whole-genome amplification may thus be necessary. This study assess the quality of DNA obtained from different amplification protocols by evaluating fidelity and robustness of the genotyping of 610,000 single nucleotide polymorphisms, using the Illumina Infinium HD Human610-Quad BeadChip. Whole-genome amplified DNA from 24 neonatal dried blood spot samples stored between 15 to 25 years was tested, and high-quality genomic DNA from 8 of the same individuals was used as reference.

Results

Using 3.2 mm disks from dried blood spot samples the optimal DNA-extraction and amplification protocol resulted in call-rates between 99.15% – 99.73% (mean 99.56%, N = 16), and conflicts with reference DNA in only three per 10,000 genotype calls.

Conclusion

Whole-genome amplified DNA from archived neonatal dried blood spot samples can be used for reliable genome-wide scans and is a cost-efficient alternative to collecting new samples.

Low-cost HIV-1 diagnosis and quantification in dried blood spots by real time PCR

Background

Rapid and cost-effective methods for HIV-1 diagnosis and viral load monitoring would greatly enhance the clinical management of HIV-1 infected adults and children in limited-resource settings. Recent recommendations to treat perinatally infected infants within the first year of life are feasible only if early diagnosis is routinely available. Dried blood spots (DBS) on filter paper are an easy and convenient way to collect and transport blood samples. A rapid and cost effective method to diagnose and quantify HIV-1 from DBS is urgently needed to facilitate early diagnosis of HIV-1 infection and monitoring of antiretroviral therapy.

Methods and Findings

We have developed a real-time LightCycler (rtLC) PCR assay to detect and quantify HIV-1 from DBS. HIV-1 RNA extracted from DBS was amplified in a one-step, single-tube system using primers specific for long-terminal repeat sequences that are conserved across all HIV-1 clades. SYBR Green dye was used to quantify PCR amplicons and HIV-1 RNA copy numbers were determined from a standard curve generated using serially diluted known copies of HIV-1 RNA. This assay detected samples across clades, has a dynamic range of 5 log₁₀, and %CV <8% up to 4 log₁₀ dilution. Plasma HIV-1 RNA copy numbers obtained using this method correlated well with the Roche Ultrasensitive (r = 0.91) and branched DNA (r = 0.89) assays. The lower limit of detection (95%) was estimated to be 136 copies. The rtLC DBS assay was 2.5 fold rapid as well as 40-fold cheaper when compared to commercial assays. Adaptation of the assay into other real-time systems demonstrated similar performance.

Conclusions

The accuracy, reliability, genotype inclusivity and affordability, along with the small volumes of blood required for the assay suggest that the rtLC DBS assay will be useful for early diagnosis and monitoring of pediatric HIV-1 infection in resource-limited settings.