Application of Normal-Phase Silica Column in Hydrophilic Interaction Liquid Chromatography Mode for Simultaneous Determination of Underivatized Amino Acids from Human Serum Samples via Liquid Chromatography-Tandem Mass Spectrometry.

In neonatal screening, amino acids have a significant diagnostic role. Determination of their values may identify abnormal conditions. Early diagnosis and continuous monitoring of amino acid disorders results in a better disease outcome. An easy and simple LC-MS/MS method was developed for the quantitation of underivatized amino acids. Amino acids were separated using a normal-phase HPLC column having a totally porous silica stationary phase and using classical reversed-phase eluents. Mass spectrometry in multiple reaction monitoring mode was used for the analysis, providing high selectivity and sensitivity. A standard addition calibration model was applied for quantitation using only one isotope-labeled internal standard for all amino acids. Five calibration points were used for quantitation, and the method was successfully validated. The slopes of the calibration curves of the individual amino acids in parallel measurements were found to be similar. Since the measured slopes were reproducible, one serum sample could represent every series of serum samples of a given day. The method was tested on human serum samples and adequate results were obtained. This new method can be easily applied in clinical laboratories.

Neonatal Screening for Cystic Fibrosis in Hungary-First-Year Experiences.

The aim of this study is to evaluate the strategy of the cystic fibrosis newborn screening (CFNBS) programme in Hungary based on the results of the first year of screening. A combined immunoreactive trypsinogen (IRT) and pancreatitis-associated protein (PAP) CFNBS protocol (IRT/IRT×PAP/IRT) was applied with an IRT-dependent safety net (SN). Out of 88,400 newborns, 256 were tested screen-positive. Fourteen cystic fibrosis (CF) and two cystic fibrosis-positive inconclusive diagnosis (CFSPID) cases were confirmed from the screen-positive cases, and two false-negative cases were diagnosed later. Based on the obtained results, a sensitivity of 88% and a positive predictive value (PPV) of 5.9% were calculated. Following the recognition of false-negative cases, the calculation method of the age-dependent cut-off was changed. In purely biochemical CFNBS protocols, a small protocol change, even after a short period, can have a significant positive impact on the performance. CFNBS should be monitored continuously in order to fine-tune the screening strategy and define the best local practices.

Identification of potential interferents of methylmalonic acid: A previously unrecognized pitfall in clinical diagnostics and newborn screening.

OBJECTIVES: Determination of methylmalonic acid (MMA) from dried blood spots (DBS) is commonly performed in clinical diagnostics and newborn screening for propionic acidemia (PA) and methylmalonic acidemia. Isobaric compounds of MMA having the same mass can affect diagnostic reliability and quantitative results, which represents a previously unrecognized pitfall in clinical assays for MMA. We set out to identify interfering substances of MMA in DBS, serum and urine samples from confirmed patients with PA and methylmalonic acidemia. METHODS: Techniques included quadrupole time-of-flight high-resolution mass spectrometry (QTOF HR-MS), nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography (LC) and tandem mass spectrometry (MS/MS). RESULTS: The five isobaric metabolites detected in DBS, serum and urine from PA and methylmalonic acidemia patients were confirmed as 2-methyl-3-hydroxybutyrate, 3-hydroxyisovalerate, 2-hydroxyisovalerate, 3-hydroxyvalerate and succinate using a series of experiments. An additional unknown substance with low abundance remained unidentified. CONCLUSIONS: The presented results facilitate the diagnostic and quantitative reliability of the MMA determination in clinical assays. Isobaric species should be investigated in assays for MMA to eliminate possible interference in a wide range of conditions including PA, methylmalonic acidemia, a vitamin B12 deficiency, ketosis and lactic acidosis.

A retrospective analysis of metabolic control in children with PKU in the COVID-19 era.

Background: Patients with phenylketonuria (PKU) must maintain a lifelong natural protein-restricted diet to prevent neuro-cognitive damage. Early diagnosis is established with newborn screening, with diet subsequently controlled by regular phenylalanine (Phe) monitoring. During the COVID-19 pandemic, significant lockdown measures were introduced that may have influenced the above. Aim of our study: To establish whether the diagnosis was delayed in neonates during the pandemic. In addition, metabolic control was further assessed during the COVID-19 pandemic era (CE) compared to the same period a year prior (non-COVID-19 era, NCE). The lockdown periods (LD) were also compared with unrestricted periods (URP). Patients methods: Six neonates born during the CE and eight neonates born during NCE were included in the newborn screening analysis. Seventy-two classical PKU patients aged 2-18 years and categorized as children (2-12 years; 51 patients) and adolescents (>13 years; 21 patients) were included in the metabolic control analysis. The frequency of dried blood spot (DBS) sampling and Phe levels were assessed according to the different periods. Results: There was no diagnostic or therapeutic delay in reaching the recommended Phe range in neonates born during CE compared to those born in NCE (median [interquartile range, IQR]: 23.5 [22.5-24] vs. 22 [18.0-27] days, p = NS). The cumulative DBS sampling frequency in children increased by 9.9% in the CE while no change was noted in the adolescent group. The median Phe level increased significantly in both age groups in the CE, but remained within the recommended target range. During CE, changes in Phe levels differed in the two age groups: children had the highest median Phe in the second lockdown period (LD2), while the adolescents had an increased Phe in URP.There were significant negative correlations between DBS sampling frequencies and Phe levels in both age groups in NCE (children: r - 0.43, p = 0.002; adolescents r = -0.37, p = 0.012), and in adolescents in CE (r = -0.62, p = 0.006). Conclusion: The pandemic did not impact newborn metabolic screening. The increased frequency of DBS sampling in CE and good target Phe levels suggest a better compliance in a very sensitive period. Since many factors may impact metabolic control in the different age groups, further studies are needed to analyse their respective role.

Quality of life in children living with PKU - a single-center, cross-sectional, observational study from Hungary.

BACKGROUND: Phenylketonuria (PKU) is an inherited error of metabolism, screened at 48-72 h of life since 1975 in Hungary. The patients have to keep a strict lifelong protein-restricted diet, resulting in PKU and its treatment can lead to social and financial burdens. The current study aimed to evaluate the health-related quality of life (HRQoL) of children living with PKU. PATIENTS AND METHODS: A single-centre, cross-sectional, observational study was conducted at the Center of Newborn Screening and Inherited Metabolic Disorders of Budapest, Hungary, using the PKU-quality of life (PKU-QoL) questionnaire. Responses of 59 parents and 11 teenagers were collected. Numerous aspects regarding HRQoL were analysed according to clinical compliance and severity. The patients were classified into groups with good or suboptimal adherence based on regular phenylalanine (Phe) values. The online officially translated versions of the adolescent or parental PKU-QoL questionnaire were used and analysed anonymously. Differences in HRQoL were compared - PKU vs. Hyperphenylalaninaemia (HPA) and good vs. suboptimal adherence. RESULTS: Twenty-five of 32 examined parameters had no or little impact on HRQoL. The most frequently reported symptom was irritability. Food enjoyment was the most impacted domain, with a major severity score in the adolescent group (median 62,5, IQR: 25-75). The emotional impact was scored at moderate severity by both the adolescents and parents. Classical PKU patients with good metabolic control were more frequently tired than HPA patients (0,0027). The group with poor metabolic adherence showed more frequent tiredness (p = 0,03), slow thinking (p = 0,018) and anxiety (p = 0,015). CONCLUSION: Overall, our patients showed an excellent HRQoL; most domains (29/36) were reported as little/no impacted. Worse QoL was found in patients with suboptimal metabolic control. Particular attention should be paid to the emotional health of PKU patients.

Correlation of GAA Genotype and Acid-α-Glucosidase Enzyme Activity in Hungarian Patients with Pompe Disease.

Pompe disease is caused by the accumulation of glycogen in the lysosomes due to a deficiency of the lysosomal acid-α-glucosidase (GAA) enzyme. Depending on residual enzyme activity, the disease manifests two distinct phenotypes. In this study, we assess an enzymatic and genetic analysis of Hungarian patients with Pompe disease. Twenty-four patients diagnosed with Pompe disease were included. Enzyme activity of acid-α-glucosidase was measured by mass spectrometry. Sanger sequencing and an MLPA of the GAA gene were performed in all patients. Twenty (83.33%) patients were classified as having late-onset Pompe disease and four (16.66%) had infantile-onset Pompe disease. Fifteen different pathogenic GAA variants were detected. The most common finding was the c.-32-13 T > G splice site alteration. Comparing the α-glucosidase enzyme activity of homozygous cases to the compound heterozygous cases of the c.-32-13 T > G disease-causing variant, the mean GAA activity in homozygous cases was significantly higher. The lowest enzyme activity was found in cases where the c.-32-13 T > G variant was not present. The localization of the identified sequence variations in regions encoding the crucial protein domains of GAA correlates with severe effects on enzyme activity. A better understanding of the impact of pathogenic gene variations may help earlier initiation of enzyme replacement therapy (ERT) if subtle symptoms occur. Further information on the effect of GAA gene variation on the efficacy of treatment and the extent of immune response to ERT would be of importance for optimal disease management and designing effective treatment plans.

Current Status of Newborn Screening in Southeastern Europe.

Significant part of Southeastern Europe (with a population of 76 million) has newborn screening (NBS) programs non-harmonized with developed European countries. Initial survey was conducted in 2013/2014 among 11 countries from the region (Albania, Bulgaria, Bosnia and Herzegovina (BIH), Croatia, Kosovo, Macedonia, Moldova, Montenegro, Romania, Serbia, and Slovenia) to assess the main characteristics of their NBS programs and their future plans. Their cumulative population at that time was ~52,5 million. At that time, none of the countries had an expanded NBS program, while phenylketonuria screening was not introduced in four and congenital hypothyroidism in three of 11 countries. We repeated the survey in 2020 inviting the same 11 countries, adding Cyprus, Greece, Hungary, and Malta (due to their geographical position in the wider region). The aims were to assess the current state, to evaluate the change in the period, and to identify the main obstacles impacting the implementation of expanded NBS and/or reaching a wider population. Responses were collected from 12 countries (BIH-Federation of BIH, BIH-Republic of Srpska, Bulgaria, Croatia, Greece, Hungary, Kosovo, North Macedonia, Malta, Montenegro, Romania, Serbia, Slovenia) with a population of 68.5 million. The results of the survey showed that the regional situation regarding NBS only modestly improved in this period. All of the surveyed countries except Kosovo screened for at least congenital hypothyroidism, while phenylketonuria was not screened in four of 12 countries. Croatia and Slovenia implemented an expanded NBS program using tandem mass spectrometry from the time of last survey. In conclusion, the current status of NBS programs in Southeastern Europe is very variable and is still underdeveloped (or even non-existent) in some of the countries. We suggest establishing an international task-force to assist with implementation and harmonization of basic NBS services where needed.

Neonatal Screening in Europe Revisited: An ISNS Perspective on the Current State and Developments Since 2010.

Neonatal screening (NBS) was initiated in Europe during the 1960s with the screening for phenylketonuria. The panel of screened disorders ("conditions") then gradually expanded, with a boost in the late 1990s with the introduction of tandem mass spectrometry (MS/MS), making it possible to screen for 40-50 conditions using a single blood spot. The most recent additions to screening programmes (screening for cystic fibrosis, severe combined immunodeficiency and spinal muscular atrophy) were assisted by or realised through the introduction of molecular technologies. For this survey, we collected data from 51 European countries. We report the developments between 2010 and 2020 and highlight the achievements reached with the progress made in this period. We also identify areas where further progress can be made, mainly by exchanging knowledge and learning from experiences in neighbouring countries. Between 2010 and 2020, most NBS programmes in geographical Europe matured considerably, both in terms of methodology (modernised) and with regard to the panel of conditions screened (expanded). These developments indicate that more collaboration in Europe through European organisations is gaining momentum. We can only accomplish the timely detection of newborn infants potentially suffering from one of the many rare diseases and take appropriate action by working together.

[Changes of lactate levels in diabetic ketoacidosis and in newly diagnosed type 1 diabetes mellitus]. / Laktátszintváltozások diabeteses ketoacidosisban és frissen diagnosztizált 1-es típusú diabetes mellitusban.

Introduction: It is known that lactate concentration is increased in diabetic ketoacidosis (DKA), however, the pathophysiology and kinetics of lactate changes are still unclear. Normally, L-lactate is the major form in the human body. According to previous data, also D- and L-lactate might be increased in hyperglycaemic disorders. Aim: We aimed to describe the kinetics and mechanisms of lactate concentration changes in ketoacidosis and newly diagnosed diabetes. Method: We performed a prospective study, including 5-18-year-old children with ketoacidosis (DKA, n = 13) and with newly diagnosed type 1 diabetes without ketoacidosis (T1DM, n = 6). We performed routine blood gas analysis 0-12-24-48 hours after admission, which also measured L-lactate levels. We also determined total venous serum lactate level by gas chromatography-mass spectrometry. Results: Initial plasma lactate concentration was increased in ketoacidosis as compared to the newly diagnosed diabetes group (p<0.05). After 12 h of rehydration, lactate levels were greatly reduced in ketoacidotic patients but after 24-48 h it was repeatedly increased (all p<0.01). In the 0-12 h phase, total serum lactate level was higher than L-lactate level, referring to D-lactate production. Conclusion: We described two L-lactate peaks in ketoacidosis. In the first 12 hours anaerobic glycolysis seems to have major role in hyperlactataemia. We assume that stimulated aerobic glycolysis leads to the second lactate peak. However, D-lactate is not routinely measured, it may contribute to the initial hyperlactataemia in both groups and is comparable to L-lactate production in ketoacidosis. Orv Hetil. 2019; 160(45): 1784-1790.

Association between interferon-induced helicase (IFIH1) rs1990760 polymorphism and seasonal variation in the onset of type 1 diabetes mellitus.

BACKGROUND: Infections, mostly of viral origin, may contribute to the seasonal variation in the onset of type 1 diabetes mellitus (T1DM). The rs1990760 (A>G, Ala946Thr) polymorphism (GG genotype) of the interferon induced helicase (IFIH1), a virus recognition receptor, confers a modest protection for T1DM. The aim of our study was to evaluate a possible association between this IFIH1 polymorphism and the seasonal variation in the onset of T1DM. MATERIALS AND METHODS: The IFIH1 rs1990760 polymorphism was genotyped in 1055 patients of Central-Eastern European ancestry with T1DM (median age at diagnosis: 8.2 [interquartile range, IQR 4.8-11.8] years). T1DM onset was recorded in monthly intervals. RESULTS: The IFIH1 genotype distribution was the following: 436 patients (41.3%) had AA genotype, 483 patients (45.8%) had AG genotype, and 136 patients (12.9%) had GG genotype. Significant seasonal variation in manifestation of T1DM (highest rate in winter and lowest rate in summer period) was observed in the total cohort (n = 1055), irrespective of gender. The disease predisposing AA genotype was more frequently found among new cases with onset in summer vs in those with onset in winter (44.3% vs 37.9%); conversely, the protective GG genotype was less frequent (9.3% vs 12.9%, respectively; P = .0268 for trend). Significant effect of genotype (P = .0418) was found on the seasonal variability of T1DM onset in the total cohort. CONCLUSIONS: The IFIH1 rs1990760 polymorphism seems to be associated with the seasonal manifestation of T1DM. Our findings suggest that this virus receptor gene may contribute to T1DM manifestation primarily in the summer period.

[Diagnostics of inborn errors of metabolism: laboratory approaches]. / Ritka örökletes anyagcsere-betegségek diagnosztikája: laboratóriumi vizsgálati megközelítések.

Inherited errors of metabolism are rare genetic disorders characterized by diverse clinical and biochemical phenotypes. The complexity of signs and symptoms often presents a challenge for both clinicians and laboratory specialists. In many cases, prevention of permanent neurological symptoms or death in patients presenting these disorders is dependent on early diagnosis and introduction of appropriate therapy. For professionals it is indispensable to be familiar with the major clinical signs of inborn errors of metabolism and with the necessary and available laboratory studies to achieve an early diagnosis. The review tries to give a way of approach, diagnostic algorithm of laboratory measurements for the correct diagnosis in inherited errors of metabolism. The combination of biochemical and clinical signs, results of special metabolic investigations represent a portentous challenge in general practice. For the correct diagnosis of an inherited error of metabolism, the teamwork between clinicians and laboratory specialists is indispensable. Orv Hetil. 2017; 158(48): 1903-1907.

Quantitative Analytical Method for the Determination of Biotinidase Activity in Dried Blood Spot Samples.

Biotinidase activity assay is included in most newborn screening protocols, and the positive results are confirmed by quantitative enzyme activity measurements. In our study, we describe a new quantitative analytical method for the determination of biotinidase activity using the blood sample deposited onto filter paper as the assay medium, by predepositing N-biotinyl-p-aminobenzoic acid onto the standard sample collection paper. The analysis of the assay mixture requires a simple extraction step from a dried blood spot followed by the quantification of product by LC-MS. The method provides a simple and reliable enzyme assay method that enables the rapid diagnosis of biotinidase deficiency (BD). Out of the measured 36 samples, 13 were healthy with lower enzyme activities, 16 were patients with partial BD, and 7 were patients with profound BD with residual activity below 10%. Expression of enzyme activity in percentage of mean activity of negative controls allows comparison of the different techniques. The obtained results are in good agreement with activity data determined from both dried blood spots and serum samples, giving an informative diagnostic value.

Metabonomics of newborn screening dried blood spot samples: a novel approach in the screening and diagnostics of inborn errors of metabolism.

A novel, single stage high resolution mass spectrometry-based method is presented for the population level screening of inborn errors of metabolism. The approach proposed here extends traditional electrospray tandem mass spectrometry screening by introducing nanospray ionization and high resolution mass spectrometry, allowing the selective detection of more than 400 individual metabolic constituents of blood including acylcarnitines, amino acids, organic acids, fatty acids, carbohydrates, bile acids, and complex lipids. Dried blood spots were extracted using a methanolic solution of isotope labeled internal standards, and filtered extracts were electrosprayed using a fully automated chip-based nanospray ion source in both positive and negative ion mode. Ions were analyzed using an Orbitrap Fourier transformation mass spectrometer at nominal mass resolution of 100,000. Individual metabolic constituents were quantified using standard isotope dilution methods. Concentration threshold (cutoff) level-based analysis allows the identification of newborns with metabolic diseases, similarly to the traditional electrospray tandem mass spectrometry (ESI-MS/MS) method; however, the detection of additional known biomarkers (e.g., organic acids) results in improved sensitivity and selectivity. The broad range of detected analytes allowed the untargeted multivariate statistical analysis of spectra and identification of additional diseased states, therapeutic artifacts, and damaged samples, besides the metabolic disease panel.