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.
The purpose of this study was to evaluate state laws regarding the retention and use of DBS.
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.
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.
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.
newborn screening; dried blood samples; research; ethics; law; consent; opt-out
State laws in the US mandate that blood be drawn from all newborn infants to screen for health-threatening conditions. These screening assays consume only a small portion of the blood samples, which are collected on filter paper (“Guthrie”) cards. Many states archive unused blood spots, often in unrefrigerated storage.
While individual RNA transcripts have been identified from archived neonatal blood spots, no study to date has performed quantitative analysis of archived blood spot RNA.
We demonstrate that RNA can be isolated and amplified from newborn blood spots stored unfrozen for as long as nine years, and can be analyzed by microarray and qPCR.
Microarray assays of archived neonatal blood spots consistently detected 3,000-4,000 expressed genes with correlations of .90 between replicates. Blood spot mRNA is amenable to qPCR and we detected biologically relevant expression levels of housekeeping and immune-mediating genes.
These experiments demonstrate the feasibility of using blood spots as a source of RNA which can be analyzed using quantitative microarray and qPCR assays. The application of these methods to the analysis of widely collected biological specimens may be a valuable resource for the study of perinatal determinants of disease development.
Guthrie; Blood Spot; RNA; Microarray; qPCR; Real-Time PCR; Neonatal Screening
State laws in the USA mandate that blood be drawn from all newborn infants to screen for health-threatening conditions. These screening assays consume only a small portion of the blood samples, which are collected on filter paper (‘Guthrie’) cards. Many states archive unused blood spots, often in unrefrigerated storage. Objectives: While individual RNA transcripts have been identified from archived neonatal blood spots, no study to date has performed quantitative analysis of archived blood spot RNA.
We demonstrate that RNA can be isolated and amplified from newborn blood spots stored unfrozen for as long as 9 years, and can be analyzed by microarray and qPCR.
Microarray assays of archived neonatal blood spots consistently detected 3,000–4,000 expressed genes with correlations of 0.90 between replicates. Blood spot mRNA is amenable to qPCR and we detected biologically relevant expression levels of housekeeping and immune-mediating genes.
These experiments demonstrate the feasibility of using blood spots as a source of RNA which can be analyzed using quantitative microarray and qPCR assays. The application of these methods to the analysis of widely collected biological specimens may be a valuable resource for the study of perinatal determinants of disease development.
Guthrie; Blood spot; RNA; Microarray; qPCR; Real-time PCR; Neonatal screening
A pilot expanded newborn screening programme to detect inherited metabolic disorders by means of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) began in the Campania region, southern Italy, in 2007. By October 2009, >8,800 dried blood samples on filter paper from 11 hospitals had been screened. Within this screening programme, we identified a case of mitochondrial acetoacetyl-coenzyme A (CoA) thiolase deficiency [β-ketothiolase (β-KT) deficiency] by analysing the acylcarnitine profile from a dried blood spot with LC-MS/MS. Gas chromatography coupled with mass spectrometry analysis of urinary organic acids and LC-MS/MS analysis of urinary acylcarnitines were in line with this disorder. In fact, concentrations were well beyond the cut-off values of tiglyl carnitine, 3-hydroxybutyrylcarnitine and 2-methyl-3-hydroxybutyrylcarnitine, 2-methyl-3-hydroxybutyric acid and tiglyl glycine. The absence of 2-methylacetoacetic acid in urine may be attributed to: (i) the instability of this β-ketoacid because it undergoes spontaneous decarboxylation to 2-butanone, which is highly volatile and thus difficult to detect, and (ii) the good health of the patient in the first days of life. β-KT deficiency was subsequently diagnosed in the patient's older sister, who showed increased levels of the same metabolites but also small amounts of 2-methylacetoacetic acid, which is considered a key marker for β-KT diagnosis. Genomic analysis revealed mutation c.1189C >G in exon 12 of the ACAT1 gene, which results in a severe defect because of the p.H397D amino acid change in both alleles of both patients.
We evaluated the performance of multiplex tandem mass spectrometry (MS/MS) in newborn screening for detection of 6 lysosomal storage disorders (LSDs), namely, Niemann-Pick A/B, Krabbe, Gaucher, Fabry, and Pompe diseases and Hurler syndrome.
We revised the conditions and procedures of multiplex enzyme assay for the MS/MS analysis and determined the precision of our enzyme assay and the effects of sample amounts and incubation time on the results. We also measured the degree of correlation between the enzyme activities in the dried blood spots (DBSs) and those in the leukocytes. DBSs of 211 normal newborns and 13 newborns with various LSDs were analyzed using our revised methods.
The intra- and inter-assay precisions were 2.9-18.7% and 8.1-18.1%, respectively. The amount of product obtained was proportional to the DBS eluate volume, but a slight flattening was observed in the product vs. sample volume curve at higher sample volumes. For each enzyme assay, the amount of product obtained increased linearly with the incubation period (range, 0-24 hr). Passing and Bablok regression analysis revealed that the enzyme activities in the DBSs and those in the leukocytes were favorably correlated. The enzyme activities measured in the DBSs were consistently lower in patients with LSDs than in normal newborns.
The performance of our revised techniques for MS/MS detection and enzyme assays was of the generally acceptable standard. To our knowledge, this is the first report on the use of MS/MS for newborn screening of LSDs in an Asian population.
Lysosomal storage disorders; Multiplex enzyme assay; Tandem mass spectrometry; Newborn screening
Fabry disease (FD) is a hereditary metabolic disorder caused by the partial or total inactivation of a lysosomal hydrolase, the enzyme α-galactosidase A (GLA). This inactivation is responsible for the storage of undegraded glycosphingolipids in the lysosomes with subsequent cellular and microvascular dysfunction. The incidence of disease is estimated at 1:40,000 in the general population, although neonatal screening initiatives have found an unexpectedly high prevalence of genetic alterations, up to 1:3,100, in newborns in Italy, and have identified a surprisingly high frequency of newborn males with genetic alterations (about 1:1,500) in Taiwan.
We describe the case of a 40-year-old female patient who presented with transient ischemic attack (TIA), discomfort in her hands, intolerance to cold and heat, severe angina and palpitations, chronic kidney disease. Clinical, biochemical and molecular studies were performed.
Reported symptoms, peculiar findings in a renal biopsy – the evidence of occasional lamellar inclusions in podocytes and mesangial cells – and left ventricular (LV) hypertrophy, which are considered to be specific features of FD, as well as molecular evaluations, suggested the diagnosis of a classical form of FD.
We detected four mutations in the GLA gene of the patient: -10C>T (g.1170C>T), c.370-77_-81del (g.7188-7192del5), c.640-16A>G (g.10115A>G), c.1000-22C>T (g.10956C>T). These mutations, located in promoter and intronic regulatory regions, have been observed in several patients with manifestations of FD. In our patient clinical picture showed a multisystemic involvement with early onset of symptoms, thus suggesting that these intronic mutations can be found even in patients with classical form of FD.
Fabry disease; α-galactosidase A; GLA; Globotriaosylceramide; High resolution melting
Screening newborns for treatable serious conditions is mandated in all US states and many other countries. After screening, Guthrie cards with residual blood (whole spots or portions of spots) are typically stored at ambient temperature in many facilities. The potential of archived dried blood spots (DBS) for at-birth molecular studies in epidemiological and clinical research is substantial. However, it is also challenging as analytes from DBS may be degraded due to preparation and storage conditions. We previously reported an improved assay for obtaining global RNA gene expression from blood spots. Here, we evaluated sex-specific gene expression and its preservation in DBS using oligonucleotide microarray technology. We found X inactivation-specific transcript (XIST), lysine-specific demethylase 5D (KDM5D) (also known as selected cDNA on Y, homolog of mouse (SMCY)), uncharacterized LOC729444 (LOC729444), and testis-specific transcript, Y-linked 21 (TTTY21) to be differentially-expressed by sex of the newborn. Our finding that trait-specific RNA gene expression is preserved in unfrozen DBS, demonstrates the technical feasibility of performing molecular genetic profiling using such samples. With millions of DBS potentially available for research, we see new opportunities in using newborn molecular gene expression to better understand molecular pathogenesis of perinatal diseases.
archived dried blood spots (DBS); sex-specific; gene expression; molecular genetic profiling; microarray
High-throughput mass spectrometry methods have been developed to screen newborns for lysosomal storage disorders, allowing the implementation of newborn screening pilot studies in North America and Europe. It is currently feasible to diagnose Pompe, Fabry, Gaucher, Krabbe, and Niemann-Pick A/B diseases, as well as mucopolysaccharidosis I, by tandem mass spectrometry in dried blood spots, which offers considerable technical advantages compared with standard methodologies. We aimed to investigate whether the mass spectrometry methodology for lysosomal storage disease screening, originally developed for newborns, can also discriminate between affected patients and controls of various ages.
A total of 205 control individuals were grouped according to age and subjected to mass spectrometry quantification of lysosomal α-glucosidase, β-glucocerebrosidase, α-galactosidase, acid sphingomyelinase, galactocerebrosidase, and α−L-iduronidase activities. Additionally, 13 affected patients were analyzed.
The median activities for each enzyme and each age group were determined. Enzyme activities were significantly lower in individuals aged older than 18 years compared with those in newborns. Affected patients presented enzymatic activities corresponding to less than 20% of the age-matched controls.
Our data indicate that the mass spectrometry methodology can be used for the screening of lysosomal storage diseases in non-newborn patients. However, for some diseases, such as Fabry and mucopolysaccharidosis I, a combination of biochemical and clinical data may be necessary to achieve accurate diagnoses.
Dried Blood Spot Analysis; Pompe Disease; Fabry Disease; Gaucher Disease; Krabbe Disease
Hemoglobinopathies are the most common inherited disorders. Newborn blood screening for clinically significant hemoglobin variants, including sickle (HbS), HbC, and HbD, has been adopted in many countries as it is widely acknowledged that early detection improves the outcome. We present a method for determination of Hb variants by direct surface sampling of dried blood spots by use of an Advion Triversa Nanomate automated electrospray system coupled to a high-resolution mass spectrometer. The method involves no sample preparation. It is possible to unambiguously identify homozygous and heterozygous HbS, HbC, and HbD variants in <10 min without the need for additional confirmation. The method allows for repeated analysis of a single blood spot over a prolonged time period and is tolerant of blood spot storage conditions.
National newborn screening programmes based on tandem-mass spectrometry (MS/MS) and other newborn screening (NBS) technologies show a substantial variation in number and types of disorders included in the screening panel. Once established, these methods offer the opportunity to extend newborn screening panels without significant investment and cost. However, systematic evaluations of newborn screening programmes are rare, most often only describing parts of the whole process from taking blood samples to long-term evaluation of outcome.
In a prospective single screening centre observational study 373 cases with confirmed diagnosis of a metabolic disorder from a total cohort of 1,084,195 neonates screened in one newborn screening laboratory between January 1, 1999, and June 30, 2009 and subsequently treated and monitored in five specialised centres for inborn errors of metabolism were examined. Process times for taking screening samples, obtaining results, initiating diagnostic confirmation and starting treatment as well as the outcome variables metabolic decompensations, clinical status, and intellectual development at a mean age of 3.3 years were evaluated.
Optimal outcome is achieved especially for the large subgroup of patients with medium-chain acyl-CoA dehydrogenase deficiency. Kaplan-Meier-analysis revealed disorder related patterns of decompensation. Urea cycle disorders, organic acid disorders, and amino acid disorders show an early high and continuous risk, medium-chain acyl-CoA dehydrogenase deficiency a continuous but much lower risk for decompensation, other fatty acid oxidation disorders an intermediate risk increasing towards the end of the first year. Clinical symptoms seem inevitable in a small subgroup of patients with very early disease onset. Later decompensation can not be completely prevented despite pre-symptomatic start of treatment. Metabolic decompensation does not necessarily result in impairment of intellectual development, but there is a definite association between the two.
Physical and cognitive outcome in patients with presymptomatic diagnosis of metabolic disorders included in the current German screening panel is equally good as in phenylketonuria, used as a gold standard for NBS. Extended NBS entails many different interrelated variables which need to be carefully evaluated and optimized. More reports from different parts of the world are needed to allow a comprehensive assessment of the likely benefits, harms and costs in different populations.
newborn screening; tandem-mass spectrometry
Newborn screening is the largest genetic screening program in the United States, with approximately four million infants screened yearly. It has been available and in continuous development for over 50 years. Each state manages, funds, and maintains its own individual program, which encompasses newborn screening as well as the diagnosis and coordination of care for affected infants and children. The ideal disorder for screening is one in which newborn intervention prevents later disabilities or death for infants who may appear normal at birth. There are 31 core conditions that are currently recommended for incorporation into state screening programs. To obtain a sample, several drops of blood are collected from the newborn’s heel and applied to filter paper. Although testing for core disorders is fairly standardized, more extensive screening varies by state and the rigorous evaluation of new disorders for inclusion in state screening panels is ongoing. As genomic medicine becomes more accessible, screening newborns for chronic diseases that may affect their long-term health will need to be addressed, as well the use of the residual blood spots for research. Obstetric providers should, at some time during pregnancy, review the basic process of newborn screening with parents to prepare them for this testing in the neonatal period. This information can be reviewed as it best suits incorporation in an individual’s practice; verbal discussion and the distribution of written materials with resources for further information is encouraged.
In the last years Italy is confronting with massive migratory movements from developing countries where hemoglobinopathies are widespread. This is causing a large diffusion and a changing spectrum in the epidemiology of hemoglobin disorders in Italy.
Investigations recently published in Italy on hemoglobinopathies among immigrants were revised in order to appreciate the impact of immigration from developing countries on epidemiology of these pathologies and to outline adequate guidelines of prevention.
Although in Italy there is a limited number of investigations regarding the relation between immigration and hemoglobin disorders, published data show that in our Nation there is a changing and increasing spectrum of hemoglobinopathies linked to immigration.
Prospective and retrospective actions of public healthy preventive policy are requested, based upon information (health educational programs for immigrants and caregivers), screenings among immigrants (school screening, pre-marital, preconception and early pregnancy screening, newborn screening), counseling for foreign at-risk couples and healthy carriers.
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.
biobanking; genetics; newborn screening; screening
This paper discusses attitudes and opinions of a diverse group of participants toward the retention and use of residual newborn blood samples for research. Data were drawn from focus groups based in six states in the USA, and results provide support for the retention and use of residual newborn blood samples for research when parental permission is asked beforehand. However, there were a number of concerns that also warrant attention for the development of policy and maintaining trust with the public, such as timing of permission, use of samples already stored, level of personal control of sample use and education. The results demonstrate the complexity of the topic and the ethical ambiguities associated with the retention and use of residual newborn blood samples.
newborn screening; focus groups; public attitudes; biobank; USA
Newborn screening was implemented in the 1960s with screening for phenylketonuria (PKU). In the same decade, it became possible to screen for classical galactosemia, a rare autosomal recessive inherited disorder, which is potentially life threatening if not treated. While newborn screening for PKU has become almost universal, galactosemia is included only in a minority of European newborn screening programs. The major arguments why galactosemia is excluded from newborn screening programs are that the disease can be diagnosed clinically, there is a high rate of false positives and long-term complications are common despite early diagnosis.
Here, we report how we have decreased the number of false-positive galactosemia recalls to less than 0.01%, using a two-tier test strategy. All samples are tested with the Beutler blood spot test, a method that measures galactose-1-phosphate uridyltransferase activity. Samples with less than ≤15% activity are tested for galactose with a galactose dehydrogenase test (the rapid GAL-DH test), which catalyzes the oxidation of galactose and the reduction of NAD+ to NADH that is estimated visually by fluorescence under UV-light. Both tests are semiquantitative.
With this strategy, screening for galactosemia is inexpensive, does not demand a heavy workload, and has a low false-positive re-call rate. The incidence of classical galactosemia in Sweden is 1/100,000, which is lower than the reported incidence in other European countries. Despite this, newborn screening for galactosemia has never been questioned.
Concise sentence: Screening for galactosemia using well-established methods to reduce the false-positive rate.
newborn screening by tandem mass spectrometry for detection of medium
chain acyl-CoA dehydrogenase (MCAD) deficiency, a fatty acid oxidation
disorder with significant mortality in undiagnosed patients.
were studied: (a) 13 clinically detected
MCAD deficient subjects, most homozygous for the common A985G mutation, whose newborn screening sample was available;
(b) 275 653 consecutive neonates undergoing
routine newborn screening. Screened infants with blood
octanoylcarnitine levels ⩾ 1 µmol/l were analysed for the A985G
mutation, had analysis of plasma and repeat blood spot acylcarnitines
and urinary organic acids, and had fibroblast fatty acid oxidation or
RESULT—Twelve of the
13 patients later diagnosed clinically had newborn octanoylcarnitine
levels > 2.3 µmol/l. Twenty three screened babies had initial
octanoylcarnitine levels ⩾ 1 µmol/l. Eleven of 12 babies with
persistent abnormalities had metabolite and/or enzyme studies
indicating MCAD deficiency. Only four were homozygous for the A985G
mutation, the remainder carrying one copy.
patients with symptomatic MCAD deficiency could be detected by newborn
screening. Infants actually detected had a lower frequency of A985G
alleles than clinically diagnosed cases and may have a lower risk of
The purpose of this study is to provide insight into the determinants of low birth weight (LBW) in Italy.
The study was carried out in a non-teaching hospital in Catanzaro (Italy). All LBW and very LBW newborns (200) were included in the study and a random sample of 400 newborns weighing ≥ 2500 g was selected. Data were collected from the delivery certificates during one year. Smoking activity of mother and familiar and/or social support during pregnancy was gathered through telephone interviews.
Overall annual LBW rate was 11.8%. Among LBW newborn there were 125 preterm and 75 term. Younger mothers, those who smoked during pregnancy, and had fewer prenatal care visits were more likely to deliver a LBW child; moreover, preterm newborns, delivered by caesarean section, and twin or multiple birth were significantly more likely to have a LBW. The comparison of very LBW (<1500 g) to LBW newborns showed that a very LBW was significantly more likely in newborns delivered by less educated mothers, those who work outside the home, live in smaller towns, and had less echographies; moreover, as expected, very LBW newborns were more likely to be preterm.
Several modifiable factors affect the risk of LBW, even when universal access to health care is freely available, but socio-economic status appears to correlate only to very LBW.
Expansion of newborn screening for inherited metabolic disorders using tandem mass spectrometry has generated interest in screening for other treatable conditions, including lysosomal storage diseases. Limitations to expansion include labor and equipment costs. We describe a cost-effective new platform that reduces the time to result reporting and can perform multiplexing assays requiring different platforms. Immunoassays and enzyme activity assays currently used in newborn screening have been translated to a disposable microchip programmed to dispense, transport, mix, wash, and incubate individual microdroplets from specimens, including dried blood spot extracts, and reagents all under software control. The specimen and reagents consumed are approximately 1% of those required by equivalent bench assays. In addition to immunologic and enzymatic assays, DNA amplification, amplicon detection, and sequencing have been demonstrated using the same microchips and control equipment. Recently, the multiplexing of 4 different enzyme activities has also been demonstrated with negligible cross-contamination. We review assays relevant to newborn screening.
newborn screening; lab-on-a-chip; lysosomal storage disease; severe combined immunodeficiency; digital microfluidics
We sought to modify a previously published tandem mass spectrometry method of screening for 5 lysosomal storage disorders (LSDs) in order to make it better suited for high-throughput newborn screening.
Two 3-mm dried blood spot (DBS) punches were incubated, each with a different assay solution. The quadruplex solution was used for screening for Gaucher, Pompe, Krabbe and Fabry diseases, while a separate solution was used for Niemann–Pick A/B disease.
The mean activities of acid-β-glucocerebrosidase (ABG), acid sphingomyelinase (ASM), acid glucosidase (GAA), galactocerebroside-β-galactosidase (GALC) and acid-galactosidase A (GLA) were measured on 5055 unidentified newborns. The mean activities (compared with their disease controls) were, 15.1 (0.35), 22.2 (1.34), 16.8 (0.51), 3.61 (0.23), and 20.7 (1.43) (μmol/L/h), respectively. The number of specimens that fell below our retest level cutoff of <20% daily mean activity (DMA) for each analyte is: ABG (6), ASM (0), GAA (5), GALC (17), and GLA (2).
This method provides a simplified and reliable assay for screening for five LSDs with clear distinction between activities from normal and disease samples. Advantages of this new method include significant decreases in processing time and the number of required assay solutions and overall decreased complexity.
Newborn screening; Lysosomal storage disorder; Multiplex; Tandem mass spectrometry
CTnDOT integrase (IntDOT) is a member of the tyrosine family of site-specific DNA recombinases. IntDOT is unusual in that it catalyzes recombination between nonidentical sequences. Previous mutational analyses centered on mutants with substitutions of conserved residues in the catalytic (CAT) domain or residues predicted by homology modeling to be close to DNA in the core-binding (CB) domain. That work suggested that a conserved active-site residue (Arg I) of the CAT domain is missing and that some residues in the CB domain are involved in catalysis. Here we used a genetic approach and constructed an Escherichia coli indicator strain to screen for random mutations in IntDOT that disrupt integrative recombination in vivo. Twenty-five IntDOT mutants were isolated and characterized for DNA binding, DNA cleavage, and DNA ligation activities. We found that mutants with substitutions in the amino-terminal (N) domain were catalytically active but defective in forming nucleoprotein complexes, suggesting that they have altered protein-protein interactions or altered interactions with DNA. Replacement of Ala-352 of the CAT domain disrupted DNA cleavage but not DNA ligation, suggesting that Ala-352 may be important for positioning the catalytic tyrosine (Tyr-381) during cleavage. Interestingly, our biochemical data and homology modeling of the CAT domain suggest that Arg-285 is the missing Arg I residue of IntDOT. The predicted position of Arg-285 shows it entering the active site from a position on the polypeptide backbone that is not utilized in other tyrosine recombinases. IntDOT may therefore employ a novel active-site architecture to catalyze recombination.
Tyrosinemia type I is a genetic disorder characterized by accumulation in the blood and urine of the toxic metabolite succinylacetone (SUAC), not detectable in healthy samples. In many countries, newborns are screened for tyrosinemia type I using tyrosine as a primary marker. Unfortunately, tyrosine accumulation may take longer to occur and it may be not obvious when specimens are collected, in the first few days of life, as for newborn screening. In 2008, we reported changes to simultaneously measure acylcarnitines, amino acids, and SUAC during expanded newborn screening. We established the usefulness of this method after identifying a first asymptomatic newborn affected by tyrosinemia type I. Now we report a second infant with positive SUAC screening result (14.1 μmol/L, n.v. < 2) and normal tyrosine concentration (74 μmol/L; n.v. < 250). We also performed molecular analysis of FAH gene in both patients after diagnosis at newborn screening. They had consanguineous parents and were both homozygous for two known disease-causing mutations of the FAH gene. The outcome of patients detected in the MS/MS screening is significantly favorable. We also report our results of newborn screening for tyrosinemia type I before and after inclusion of SUAC as a primary marker for this disease.
Newborn screening; Succynilacetone; Tyrosinemia type I
The purpose of this study was to evaluate the diagnostic performance of LIAISON Treponema Screen (DiaSorin, Saluggia, Italy), a new automated chemiluminescence immunoassay (CLIA), in comparison with that of rapid plasma reagin (RPR) and the following currently used treponemal tests: hemagglutination test (TPHA), immunoenzymatic assay (EIA), and Western blot (WB). First, a retrospective study was performed with a panel of 2,494 blood donor sera, a panel of 131 clinical and serologically characterized syphilitic sera, and 96 samples obtained from subjects with potentially interfering diseases or conditions. A prospective study was also performed by testing 1,800 unselected samples submitted to the Microbiology Laboratory of the St. Orsola Hospital in Bologna, Italy, for routine screening for syphilis. As expected, RPR was the least specific method, especially when potentially cross-reacting sera were tested. On the contrary, all of the treponemal tests proved to be very specific (99.9%) and they performed with the following sensitivities: 100% (WB), 99.2% (CLIA), 95.4% (EIA), and 94.7% (TPHA).
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.
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.
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.
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.
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.
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.
In continued efforts to develop enzymatic assays for lysosomal storage diseases appropriate for newborn screening laboratories we have synthesized novel and specific enzyme substrates for Maroteaux-Lamy (MPS VI) and Morquio A (MPS IVA) diseases. The sulfated monosaccharide derivatives were found to be converted to product by the respective enzyme in blood from healthy patients but not by blood from patients with the relevant lysosomal storage disease. The latter result shows that the designed substrates are highly selective for the respective enzymes.