Newborn Screening Blood Spots Research Articles

Tandem mass spectrometric enzyme assay for simultaneous detection of Tay-Sachs and Sandhoff diseases in dried blood spots for newborn screening

GM2 gangliosidosis is a group of rare lysosomal storage disorders (LSDs) including Tay-Sachs disease (TSD) and Sandhoff disease (SD), caused by deficiency in activity of either β-hexosaminidase A (HexA) or both β-hexosaminidase A and β-hexosaminidase B (Hex B). Methods for screening and diagnosis of TSD and SD include measurement and comparison of the activity of these two enzymes. Here we report a novel method for duplex screening of dried blood spots (DBS) for TSD and SD by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method requires incubation of a single 3 mm DBS punch with the assay cocktail followed by the injection into the LC-MS/MS. The performance of the method was evaluated by comparing the confirmed TSD and SD patient DBS to random healthy newborn DBS which showed easy discrimination between the three cohorts. The method is multiplexable with other LSD MS/MS enzyme assays which is critical to the continued expansion of the NBS panels.

The Benefit of Detecting Reduced Intracellular B12 Activity through Newborn Screening Remains Unclear.

Vitamin B12 (B12) deficiency (B12D) can have detrimental effects on early growth and development. The Austrian newborn screening (NBS) program targets inborn errors of cobalamin metabolism and also detects B12D. Of 59 included neonates with B12D suspected by NBS, B12D was not further investigated in 16 (27%) retrospectively identified cases, not confirmed in 28 (48%), and confirmed in 15 (25%) cases. NBS and recall biomarkers were recorded. Age at sampling of the dried blood spots for NBS and the 1st-tier methionine/phenylalanine ratio were the strongest parameters to predict B12D (67.4% correct allocations). No differences between cases with confirmed, unconfirmed, or unknown B12D or differences to norms were observed for growth and psychomotor development (Vineland III scales, phone interviews with parents of children between months 10 and 14 of life). B12 intake was below recommendations in most mothers. NBS can detect reduced intracellular B12 activity. No advantage of NBS detection and treatment regarding infant cognitive development or growth could be proven. Since conspicuous NBS findings cannot be ignored, and to prevent exposing newborns to invasive diagnostics, assessment of maternal B12 status during pregnancy seems advisable.

Understanding Gaps in Current Practices of Newborn Screening Follow-up for Sickle Cell Disease in the United States

Introduction: Newborn screening (NBS) for sickle cell disease (SCD) has significantly improved childhood survival. However, gaps remain in follow-up after NBS as demonstrated by poor implementation of penicillin prophylaxis and stroke risk (TCD) screening. It is unknown how time to initial engagement with SCD specialist may impact long-term patient engagement. Currently, there are no standardized follow-up requirements for NBS across the United States; each state can decide how they inform families of diagnoses and initiate follow-up. The average time to the initial follow-up with a SCD specialist is not currently evaluated as a measure of quality assurance. Semi-structured interviews were conducted with 19 participants across 11 states to explore NBS processes. Participants included health care providers (n = 7), and stakeholders (NBS health department employees and community based SCD organization representatives (CBO); (n = 12). Data were analyzed using directed content analysis, informed by the SCD care continuum model, which outlines how newborns with SCD should proceed from diagnosis to initial and ongoing care engagement with a SCD provider. We examined how families were informed of abnormal results, how newly-diagnosed children were referred to SCD specialists, and when cases were closed. Results Representatives from 11 states including AL, AK, CA, GA, LA, MI, MS, MO, NY, SC, TN were included in this study (Table 1). Initial Notification: In all 11 states, the physician of record (on the NBS bloodspot card) is notified of abnormal results and expected to communicate results to families. This physician of record is not necessarily the child's actual pediatrician. In 2 states, a letter is sent to families at the same time as physicians are notified, but the letter does not convey screening results. In 1 state, the CBO NBS coordinator is responsible for communicating results to the family. Referral to a SCD specialist: There was substantial variability in referral practices. In most states, infants with positive SCD screens were referred to a SCD specialist by the pediatrician. In some states, the public health department refers infants with positive screens directly to the SCD center. In 2 states, the decision to refer an infant to a SCD center is left to the family, NBS coordinator or CBO. Timing of first visit: Most states intend infants with positive SCD screens to follow-up with the SCD clinic in < 2 months; however, some states do not require the initial visit until 6 months. Notably, most states do not track whether children with a positive SCD screen ever see a SCD specialist, Instead, cases are closed once the physician of record is informed. Facilitators and Barriers: The most common facilitators for communicating NBS results were having the correct physician of record on the blood spot card, the physician's knowledge of SCD, or the use of state-based immunization databases to track children with missing demographic information. Key facilitators for linkage to care included partnerships with SCD CBOs and/or having designated NBS follow up coordinators that offer ongoing family education and appointment reminders. Other facilitators included families with extended support and those who already had a child with SCD. The most common barriers to communicating NBS results were difficulty locating or reaching families, families moving out of state, insufficient contact information, and/or having the wrong physician of record. The main barriers to linkage to care included lack of insurance, lack of transportation, families who have difficulty accepting the SCD diagnosis, immigrant or refugee families with language barriers and other conflicting social/life demands. Conclusion The results of our study demonstrate wide variability in NBS follow-up for SCD with limited quality assurance to ensure newborns see a SCD specialist. These findings indicate a large multi-level intervention trial is needed to identify best practices for systematic improvement in NBS follow up process and ensure all infants are seen by a SCD specialist.

Dicarboxylic acylcarnitine biomarkers in peroxisome biogenesis disorders

The peroxisome is an essential eukaryotic organelle with diverse metabolic functions. Inherited peroxisomal disorders are associated with a wide spectrum of clinical outcomes and are broadly divided into two classes, those impacting peroxisome biogenesis (PBD) and those impacting specific peroxisomal factors. Prior studies have indicated a role for acylcarnitine testing in the diagnosis of some peroxisomal diseases through the detection of long chain dicarboxylic acylcarnitine abnormalities (C16-DC and C18-DC). However, there remains limited independent corroboration of these initial findings and acylcarnitine testing for peroxisomal diseases has not been widely adopted in clinical laboratories. To explore the utility of acylcarnitine testing in the diagnosis of peroxisomal disorders we applied a LC-MS/MS acylcarnitine method to study a heterogenous clinical sample set (n = 598) that included residual plasma specimens from nineteen patients with PBD caused by PEX1 or PEX6 deficiency, ranging in severity from lethal neonatal onset to mild late onset forms. Multiple dicarboxylic acylcarnitines were significantly elevated in PBD patients including medium to long chain (C8-DC to C18-DC) species as well as previously undescribed elevations of malonylcarnitine (C3-DC) and very long chain dicarboxylic acylcarnitines (C20-DC and C22-DC). The best performing plasma acylcarnitine biomarkers, C20-DC and C22-DC, were detected at elevated levels in 100% and 68% of PBD patients but were rarely elevated in patients that did not have a PBD. We extended our analysis to residual newborn screening blood spot cards and were able to detect dicarboxylic acylcarnitine abnormalities in a newborn with a PBD caused by PEX6 deficiency. Similar to prior studies, we failed to detect substantial dicarboxylic acylcarnitine abnormalities in blood spot cards from patients with x-linked adrenoleukodystrophy (x-ald) indicating that these biomarkers may have utility in quickly narrowing the differential diagnosis in patients with a positive newborn screen for x-ald. Overall, our study identifies widespread dicarboxylic acylcarnitine abnormalities in patients with PBD and highlights key acylcarnitine biomarkers for the detection of this class of inherited metabolic disease.

New-born screening of metabolites with liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry: a metabolic and molecular signatures methyl malonic aciduria with combined oxidative phosphorylation deficiency-10: a rare case report

An uncommon autosomal recessive organic acid disease is malonic aciduria. This disease may be easily identified and included in the NBS programmes by means of the widespread use of tandem mass spectrometry’s in the study of the amino acid/acylcarnitine profile using dried blood spots (DBS) for newborn screening. In Tamil Nadu, we reported the first screened and diagnosed with malonic aciduria by newborn screening (NBS) in early neonatal period. The patient possesses a malonyl-CoA decarboxylase genetic variation not previously described. This disease should be distinguished from a related malonic and methylmalonic aciduria problem. Malonic aciduria's clinical phenomenology varies and pathogenesis is not completely known. The proper treatment regimen, nutritional therapy or frequent follow-up to these individuals are not guided or recommended. The majority of current treatment data is based on a single research or case report.

Outcomes of lowered newborn screening thresholds for congenital hypothyroidism.

Newborn screening (NBS) has largely eliminated the physical and neurodevelopmental effects of untreated congenital hypothyroidism (CH). Many countries, including Australia, have progressively lowered NBS bloodspot thyroid-stimulating hormone (b-TSH) thresholds. The impact of these changes is still unclear. To evaluate the performance of CH NBS following the reduction of b-TSH thresholds in New South Wales (NSW) and the Australian Capital Territory (ACT), Australia, from 15 to 8 mIU/L, and to determine the clinical outcomes of cases detected by these thresholds. NBS data of 346 849 infants born in NSW/ACT, Australia from 1 November, 2016-1 March, 2020 inclusive were analysed. A clinical audit was conducted on infants with a preliminary diagnosis of CH born between 1 January, 2016-1 December, 2020 inclusive. The lowered b-TSH threshold (≥8 mIU/L, ~99.5th centile) detected 1668 infants (0.48%), representing an eight-fold increase in recall rate, of whom 212 of 1668 (12.7%) commenced thyroxine treatment. Of these 212 infants, 62 (29.2%) (including eight cases with a preliminary diagnosis of thyroid dysgenesis) had an initial b-TSH 8-14.9 mIU/L. The positive predictive value for a preliminary diagnosis of CH decreased from 74.3% to 12.8% with the lowered threshold. Proportionally, more pre-term infants received a preliminary CH diagnosis on screening with the lower threshold (16.1% of 62) than with the higher threshold (8.0% of 150). Clinically relevant CH was detected using the lowered threshold, albeit at the cost of an eight-fold increase in recall rate. Further clinical and economic studies are required to determine whether benefits of lowered screening thresholds outweigh potential harms from false-positive results on infants, their families and NBS programs.

P552: Improving DNA sequencing from dried blood spots for multi-tiered newborn screening

P552: Improving DNA sequencing from dried blood spots for multi-tiered newborn screening

Abstract 11554: Biochemical and Molecular Newborn Screening for Familial Hypercholesterolemia

Introduction: Familial Hypercholesterolemia (FH) is a common genetic disorder resulting in elevated low-density lipoprotein cholesterol (LDL-C) causing premature atherosclerosis. Despite guidelines, universal screening rates remain low. Newborn screening could increase FH diagnostic rates. Hypothesis: Biochemical newborn screening for LDL-C, total cholesterol (TC), and apolipoprotein B (apoB) followed by selective molecular testing identifies pathogenic and likely pathogenic variants causing FH. Methods: De-identified, residual newborn screening bloodspots collected for routine screening at 24-48 hours of life were analyzed for LDL-C, TC, and apoB. Values are expressed as multiples of median (MoM). Mahalanobis distance, measuring how far MoM values differed positively from 1, was computed. Samples with the most extreme Mahalanobis distance were selected for molecular testing (panel includes LDLR , APOB , PCSK9 , LDLRAP1 , APOE , STAP1 , LIPA , ABCG5 , and ABCG8 ). Results: Distributions of apoB, TC, and LDL-C from 5,248 samples are shown below (figure). ApoB followed a Gamma distribution; TC and LDL-C followed non-normal but symmetric distributions. ApoB and LDL-C accounted for 93% of variance among biomarkers. Of the first 2500 samples, 192 samples were selected for molecular testing; a pathogenic variant for monogenic FH was detected in 1 sample and risk factors for polygenic FH in 4 samples (table below). Conclusions: Pathogenic or likely pathogenic variants for FH were identified with an incidence of 1 in 500 in the first 2500 newborn specimens tested. Further study will determine if this two-tiered screening strategy adequately detects FH in newborns.

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.

Metabolite Identification Using Infrared Ion Spectroscopy─Novel Biomarkers for Pyridoxine-Dependent Epilepsy.

Untargeted liquid chromatography–mass spectrometry (LC–MS)-based metabolomics strategies are being increasingly applied in metabolite screening for a wide variety of medical conditions. The long-standing “grand challenge” in the utilization of this approach is metabolite identification—confidently determining the chemical structures of m/z-detected unknowns. Here, we use a novel workflow based on the detection of molecular features of interest by high-throughput untargeted LC–MS analysis of patient body fluids combined with targeted molecular identification of those features using infrared ion spectroscopy (IRIS), effectively providing diagnostic IR fingerprints for mass-isolated targets. A significant advantage of this approach is that in silico-predicted IR spectra of candidate chemical structures can be used to suggest the molecular structure of unknown features, thus mitigating the need for the synthesis of a broad range of physical reference standards. Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is an inborn error of lysine metabolism, resulting from a mutation in the ALDH7A1 gene that leads to an accumulation of toxic levels of α-aminoadipic semialdehyde (α-AASA), piperideine-6-carboxylate (P6C), and pipecolic acid in body fluids. While α-AASA and P6C are known biomarkers for PDE in urine, their instability makes them poor candidates for diagnostic analysis from blood, which would be required for application in newborn screening protocols. Here, we use combined untargeted metabolomics–IRIS to identify several new biomarkers for PDE-ALDH7A1 that can be used for diagnostic analysis in urine, plasma, and cerebrospinal fluids and that are compatible with analysis in dried blood spots for newborn screening. The identification of these novel metabolites has directly provided novel insights into the pathophysiology of PDE-ALDH7A1.

Evaluation of newborn screening for severe combined immunodeficiency (SCID).

Important features about a screening programme for newborn infants are that it should accurately, without too many false positives, detect a disease that is serious, where effective management is readily available and early presymptomatic detection and intervention should reduce morbidity and mortality. The screening test must be applicable to the general neonatal population and the whole programme should have an acceptable cost, relative to the potential benefit. A definitive followup test that distinguishes true positives from false positives should be readily available. Following diagnosis, treatment should be instituted in a timely manner. It is essential that the programme is subjected to appropriate monitoring and quality assurance to ensure that the intended outcome is delivered. Most diseases detected by newborn screening are rare, and severe combined immunodeficiency (SCID) is no exception. Affecting approximately 14 infants a year in England, SCID is caused by mutations in one of a number of genes responsible for development of T-lymphocytes. Affected infants appear well at birth but present by a few months of age with recurrent or persistent infection and failure to thrive. The condition is usually fatal by 12–18 months of age without bone marrow transplantation.1 By measuring ‘waste’ DNA, produced during lymphocyte receptor formation (TRECs), on the newborn screening blood spot card, SCID can be detected and confirmed by flow cytometry.2 To find out how devastating the disease is for a family, we have asked Rebecca to tell us about her experience. ‘I’m Rebecca and I’m a parent of three …

The Value of Cognitive Pretesting: Improving Validity and Revealing Blind Spots through the Development of a Newborn Screening Parent Experiences Survey.

Surveys are used to gather a range of data on newborn screening (NBS) processes. We describe the development of a survey about parents’ NBS experiences, in the United States, informed by cognitive pretest interviews among parents with varying NBS test results (true-positive, false-positive, normal). Cognitive pretest interviews were conducted following a semi-structured script and notes were taken to identify problematic survey items. The study team met weekly to discuss pretest feedback, draft changes, and generate revised items. Pretests indicated that parent experiences with NBS are varied and NBS screening procedures are not well understood. Substantial modifications were made to survey questions concerning NBS testing and result communication. Pretesters often associated NBS with other tests/exams/scales—APGAR scores, Ages and Stages questionnaires, and genetic testing during pregnancy. Some pretesters recalled receiving NBS blood spot results during their hospital admission, an uncommon practice, and few recalled knowing results would be provided to them or their pediatrician in the first few weeks of life. Thorough explanations regarding NBS procedures and expectations were embedded within the survey to enhance and improve interpretation of survey questions. Future NBS experience surveys should utilize cognitive pretesting to capture divergent experiences and improve response validity.

Implementing steroid profiling by liquid chromatography-tandem mass spectrometry improves newborn screening for congenital adrenal hyperplasia in New Zealand.

To evaluate the impact of a liquid chromatography-tandem mass spectrometry (LCMSMS) second-tier test on newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH) in New Zealand. In a prospective study, a LCMSMS method to measure 17-hydroxyprogesterone (17OHP) was adapted to measure four additional steroids. Steroid concentrations were collected on all second-tier CAH screening tests while protocols remained unchanged. Steroid ratio parameters with recommended or published screening cuts-offs were evaluated for their impact on newborn screening performance. Precision, accuracy, linearity and recovery of the second-tier LCMSMS method were evaluated. Second-tier specimens were divided in 3 groups; newborn screening bloodspots from neonates with confirmed CAH (n=7) and 2 groups specimens from neonates with a birthweight (BW) ≤1500g (n=795) and with a BW>1500g (n=806) with a negative newborn screening test. Six protocols using four steroid ratio parameters were evaluated. The sensitivity, specificity, false positive rate and positive predictive value of screening was calculated for each protocol. The LCMSMS method was sufficiently accurate and precise to be used as a second-tier test for CAH. Screening sensitivity remained at 100% for each protocol apart from (17OHP+androstenedione)/cortisol when the highest cut-off of 3.75 was applied. The false positive rate was significantly improved when (17OHP+androstenedione)/cortisol and (17OHP+21-deoxycortisol)/cortisol were evaluated with cut-offs of 2.5 and 1.5 respectively (P<.01) and both with a positive predictive value of 64%. A second-tier LCMSMS newborn screening test for CAH offers significant improvements to screening specificity without any other changes to screening protocols.

Utility of measuring very long-chain fatty-acyl carnitines in dried blood spots for newborn screening of X-linked Adrenoleukodystrophy

We measured C24:0 and C26:0-carnitines in dried blood spots by flow injection analysis-tandem mass spectrometry method to evaluate whether they can be used as markers for newborn screening of X-linked Adrenoleukodystrophy (X-ALD). We found that C26:0-carnitine was 95.1% and 44.7% sensitive for identifying male X-ALD cases and heterozygous females, respectively. False negatives were found for C24:0-carnitine (11/82) and C26:0-carnitine (4/82). We conclude that C24:0 and C26:0-carnitines may not be reliable markers for X-ALD screening.

Second-Tier Next Generation Sequencing Integrated in Nationwide Newborn Screening Provides Rapid Molecular Diagnostics of Severe Combined Immunodeficiency.

Severe combined immunodeficiency (SCID) and other T cell lymphopenias can be detected during newborn screening (NBS) by measuring T cell receptor excision circles (TRECs) in dried blood spot (DBS) DNA. Second tier next generation sequencing (NGS) with an amplicon based targeted gene panel using the same DBS DNA was introduced as part of our prospective pilot research project in 2015. With written parental consent, 21 000 newborns were TREC-tested in the pilot. Three newborns were identified with SCID, and disease-causing variants in IL2RG, RAG2, and RMRP were confirmed by NGS on the initial DBS DNA. The molecular findings directed follow-up and therapy: the IL2RG-SCID underwent early hematopoietic stem cell transplantation (HSCT) without any complications; the leaky RAG2-SCID received prophylactic antibiotics, antifungals, and immunoglobulin infusions, and underwent HSCT at 1 year of age. The child with RMRP-SCID had complete Hirschsprung disease and died at 1 month of age. Since January 2018, all newborns in Norway have been offered NBS for SCID using 1st tier TRECs and 2nd tier gene panel NGS on DBS DNA. During the first 20 months of nationwide SCID screening an additional 88 000 newborns were TREC tested, and four new SCID cases were identified. Disease-causing variants in DCLRE1C, JAK3, NBN, and IL2RG were molecularly confirmed on day 8, 15, 8 and 6, respectively after birth, using the initial NBS blood spot. Targeted gene panel NGS integrated into the NBS algorithm rapidly delineated the specific molecular diagnoses and provided information useful for management, targeted therapy and follow-up i.e., X rays and CT scans were avoided in the radiosensitive SCID. Second tier targeted NGS on the same DBS DNA as the TREC test provided instant confirmation or exclusion of SCID, and made it possible to use a less stringent TREC cut-off value. This allowed for the detection of leaky SCIDs, and simultaneously reduced the number of control samples, recalls and false positives. Mothers were instructed to stop breastfeeding until maternal cytomegalovirus (CMV) status was determined. Our limited data suggest that shorter time-interval from birth to intervention, may prevent breast milk transmitted CMV infection in classical SCID.

T-cell Receptor Excision Circles in Newborns with Heart Defects

In the fetus, the cardiac neural crest gives rise to both the thymus and the conotruncus of the heart. In newborn screening for severe T-cell lymphopenia neonates with congenital heart defects may be detected. In this study, we investigated the occurrence of T-cell lymphopenia in neonates with or without 22q11.2 deletion syndrome (del) suffering from heart defects. This retrospective cohort study included 125 patients with heart defects. T-cell receptor excision circles (TRECs), a measure for T-cell lymphopenia, were quantified by RT-PCR using stored newborn screening blood spots. Three patient groups were compared: non-conotruncal defects (n = 57), conotruncal defects (n = 42), and 22q11.2 del with conotruncal defects (n = 26). Significantly lower TREC values were detected in patients with 22q11.2 del and conotruncal heart defects compared to those with non-syndromic conotruncal (p < 0.001) and non-conotruncal (p < 0.001) defects. In contrast, no significant difference was found between patients with non-syndromic conotruncal and non-conotruncal heart defects (p = 0.152). Low TREC levels were obtained in neonates treated with heart surgery/intervention within 2 weeks after birth and in those with a fatal outcome (p = 0.02) independent of patient group. A correlation was found between low TREC numbers and oxygen saturation, SpO2 below 95% (p = 0.017). The SpO2 was significantly lower in the non-syndromic conotruncal group compared to non-conotruncal (p < 0.001) and 22q11.2 del group (p = 0.015). No correlation was found between low neonatal TRECs and infections needing hospitalization later in life (p = 0.135). Patients with 22q11.2 del and conotruncal defects have significantly lower TREC levels compared to patients with heart defects without this syndrome.

Prediction of VLCAD deficiency phenotype by a metabolic fingerprint in newborn screening bloodspots

PurposeNewborns who test positive for very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) in newborn screening may have a severe phenotype with early onset of life-threatening symptoms but may also have an attenuated phenotype and never become symptomatic. The objective of this study is to investigate whether metabolomic profiles in dried bloodspots (DBS) of newborns allow early phenotypic prediction, permitting tailored treatment and follow-up. MethodsA metabolic fingerprint was generated by direct infusion high resolution mass spectrometry in DBS of VLCADD patients (n = 15) and matched controls. Multivariate analysis of the metabolomic profiles was applied to differentiate subgroups. ResultsConcentration of six acylcarnitine species differed significantly between patients and controls. The concentration of C18:2- and C20:0-carnitine, 13,14-dihydroretinol and deoxycytidine monophosphate allowed separation between mild and severe patients. Two patients who could not be prognosticated on early clinical symptoms, were correctly fitted for severity in the score plot based on the untargeted metabolomics. ConclusionDistinctive metabolomic profiles in DBS of newborns with VLCADD may allow phenotypic prognostication. The full potential of this approach as well as the underlying biochemical mechanisms need further investigation.

Informing New Mothers about Newborn Screening Bloodspot Repositories during Postpartum Hospitalization.

The primary goals of the study were to assess maternal knowledge and attitudes about the newborn screening bloodspot repository program in Texas and to evaluate the effect of a video about the bloodspot repository on the rate of parental permission to store infant bloodspots. This descriptive, comparative study used descriptive statistics, nonparametric tests, and multivariable analyses to describe the sample, compare groups, and determine associations between factors that influenced parents' decisions to permit state storage of infant bloodspots. There were 465 mothers in the study. Maternal knowledge about basic genetics and risks of genetic testing was poor, but mothers reported strong trust in the state to make good decisions about using genetic material for research. Race, ethnicity, and attitude toward research significantly influenced decisions to opt-in to the bloodspot storage program. Postpartum nurses provided the bulk of information about newborn screening and dried bloodspots, although 2/3 of respondents would have preferred to obtain this information prior to birth. Although postpartum nurses are the most common source of information about newborn screening, genuine informed consent for bloodspot storage is questionable. Information about newborn screening and bloodspot storage needs to be addressed in community venues prior to birth.

Newborn screening program and blood amino acid profiling in early neonates with citrin deficiency

Objective: To investigate the profiles of blood amino acid and acylcarnitine in early neonates with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and the sensitivity of newborn screening, and to explore potential biochemical metabolic markers for newborn screening program. Methods: Amino acid and acylcarnitine profiles in dried blood spots of newborn screening program were analyzed by tandem mass spectrometry (MS/MS). A total of 158 651 neonates born in Guangzhou from January 1, 2015 to June 30, 2019 were enrolled in this newborn screening program, and additionally 55 patients with NICCD confirmed by SLC25A13 gene analysis in Guangzhou Women and Children Medical Center were included in this study. NICCD screen-positive was defined as the cutoff value of citrulline (Cit) ≥ 30 μmol/L. The values of blood sampling time of the true positive group and those of the false negative group were compared by t-test. The levels of amino acid and acylcarnitine among different groups, including true positive group (Cit≥30 μmol/L), false negative group (Cit 21-<30 μmol/L and Cit<21 μmol/L) and the normal control group, were analyzed by F test, respectively. Results: Among 158 651 neonates, 39 neonates were positive for NICCD screening. Three of them were confirmed NICCD and 4 cases were found to be false negatives. The positive predictive value was 7.7% and the sensitivity was about 43.0%. Among 55 patients with NICCD, 18 cases (18/55, 32.7%) were true positives and 37 cases (37/55, 67.3%) were false negatives based on the cutoff value of citrulline in the dried blood spots for newborn screening. The blood sampling time was significantly different between true positive group and false negative group ((4.28±1.6) vs. (2.98±0.74) d, t=4.06, P<0.01). The increased levels of tyrosine((176.0±98.4) μmol/L), methionine ((37.0±26.9) μmol/L) and phenylalanine ((133.0±80.9)μmol/L) in Cit≥30 μmol/L group (n=18) were significantly different as compared with those in the other three groups, respectively (F=117.0, 58.5, 135.0, P<0.01). The levels of arginine ( (10.0±9.2) , (11.0±9.3) , (9.0±17.8) μmol/L), valine ( (119.0±29.8) , (107.6±14.1) , (102±68) μmol/L) and leucine ( (167.0±37.1) , (161.0±37.7) , (163.5±180.6) μmol/L) were not statistically significant among groups of Cit≥30 μmol/L(n=18), Cit21-<30 μmol/L(n=7) and Cit<21μmol/L(n=30,P>0.05), but they were significantly higher than those of the normal control group ((4±3), (78±21), (114.0±31.5) μmol/L, n=1 000), respectively(F=30.1, 23.0, 29.8, P<0.01). Alanine (Ala) ( (150±50) , (156.0±30.2), (168±105), (152±52) μmol/L) levels showed no significant difference (F=0.86, P>0.05) but the ratios of Ala/Cit (1.52±1.44, 6.82±1.56, 12.06±7.71, 19.42±6.27) decreased significantly among the four groups (F=69.0, P<0.05). The acylcarnitine levels showed no statistically significant results among the different groups (P>0.05). With Cit≥30 μmol/L and Ala/Cit<7.5 as cutoff values, the number of screen-positive cases reduced from 39 to 22 cases with no additional false negative case. With Cit≥21 μmol/L and Ala/Cit<7.5 as cutoff values the number of screen-positive cases increased to 117 cases with 1 additional true positive. Conclusions: The profiles of blood amino acid in early neonates with NICCD present the increased levels of multiple amino acids including citrulline, tyrosine, methionine and phenylalanine, and decreased ratio of Ala/Cit. Taking citrulline and ratio of Ala/Cit as screening markers can improve the positive predictive value appropriately. The limited sensitivity of NICCD newborn screening may be related to early blood sampling time.

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