International Journal of Neonatal Screening最新文献

Background: Monocarboxylate-transporter-8-(MCT8) deficiency, or Allan-Herndon-Dudley syndrome (AHDS), is a rare X-linked disorder caused by pathogenic variants in the SLC16A2 gene, leading to impaired transport of thyroid hormones, primarily T3 and T4, across cell membranes. The resulting central hypothyroidism and peripheral hyperthyroidism cause neurodevelopmental impairment and thyrotoxicosis. Despite the availability of therapy options, e.g., with triiodothyroacetic acid (TRIAC), diagnosis is often delayed, partly due to normal TSH levels or incomplete genetic panels. MCT8 deficiency is not yet included in newborn-screening programs worldwide.

Case description: We present a case of an infant genetically diagnosed with MCT8 deficiency at 5 months of age after presenting with muscular hypotonia, lack of head control, and developmental delay. Thyroid function testing revealed a normal TSH, low free T4, and significantly elevated free T3 and free T3/T4 ratio. Treatment with TRIAC (Emcitate^®) was initiated promptly, with close drug monitoring. Despite persistent motor deficits and dystonia, some developmental progress was observed, as well as reduction in hyperthyroidism.

Discussion/conclusions: This case underscores the importance of early free T3 and fT3/fT4 ratio testing in infants with unexplained developmental delay. Broader inclusion of SLC16A2 in genetic panels and consideration of newborn screening could improve early diagnosis and outcomes in this rare but treatable condition.

Congenital hypothyroidism (CH) is a heterogeneous condition present at birth, resulting in severe-to-mild thyroid hormone deficiency. This condition is difficult to recognize shortly after birth. Therefore, many countries worldwide have implemented newborn screening (NBS) programs for CH since the 1970s. The most recent European guidelines strongly recommend screening for primary CH, as well as for central CH when financial resources are available. However, no consensus has been reached yet to screen more rare forms of CH, such as Allan-Herndon-Dudley syndrome (AHDS), an X-linked condition linked to mutations in the gene encoding a transmembrane monocarboxylate transporter (MCT8), resistance to thyroid hormone beta (RTHβ), and resistance to thyroid hormone alfa (RTHα). The combined measurement of thyroid-stimulating hormone (TSH) and total thyroxine (TT4) on DBS currently allows the recognition of central CH (TSH low/normal and low TT4 without defects in transport proteins). With the introduction of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) for measurement of free triiodothyronine (FT3) and free thyroxine (FT4), it would be possible to screen for RTHβ (TSH normal/high and high FT4). More complicated would be the method to screen RTHα. It would require the combined measurement of FT4 and FT3 and the determination of FT3/FT4 ratio, while the combined measurement of FT3 and reverse T3 (rT3) to calculate FT3/rT3 ratio would be useful to screen AHDS. In this article, we provide some reflections on expanding NBS for primary CH also to other rare forms of CH.

Three targeted therapies are currently available for spinal muscular atrophy (SMA), which have dramatically changed the natural history of this severe and potentially fatal disease. More than 95% of SMA cases have a homozygous deletion of exon 7 of the SMN1 gene. Disease expression mainly depends on the copy number of SMN2, a hypomorphic copy of SMN1. Many countries in the world have implemented newborn screening (NBS) programs for early identification and treatment of children with SMA. We herein present the first two-year results of the SMA NBS program in Campania, a region with one of the highest birth rates in Italy. Genomic DNA was extracted from dried blood spots (DBS) and peripheral blood. For DBS, the SMN1 gene copy number was evaluated by quantitative polymerase chain reaction (qPCR) targeting SMN1 exon 7 and a reference gene (RPP30). In positive newborns and their parents, SMN1/SMN2 copies were evaluated by multiplex ligation probe amplification (MLPA). We analyzed 77,945 newborns and identified 11 positive children. Six patients had 2 copies of SMN2, but only one showed severe SMA-related signs at birth. Eligible newborns were treated with gene therapy within 20 days of birth. Notably, qPCR failed to amplify the reference RPP30 gene in 10/77,945 DBS. Despite this limitation, we observed that about 1/40 DBS had ΔCt values consistent with the presence of one SMN1 copy. The semi-automated procedure used for SMA NBS showed excellent performance in detecting the presence of homozygous deletion of SMN1 exon 7, with the exception of a few cases with the absence of amplification of the reference gene. By solving this limitation, the screening procedure has the potential to detect heterozygous carriers of the SMN1 deletion and, consequently, identify families at procreative risk of SMA.

Seasonal and environmental factors, including temperature, humidity, and storage conditions, significantly impact the stability of biochemical markers in dried blood spot (DBS) samples. This study investigates these influences specifically for adenosine (ADO) levels, a critical biomarker for neonatal screening of adenosine deaminase (ADA) deficiency. This study analyzed seasonal fluctuations in ADO concentrations across three regions in China (Ningbo, Nanjing, and Changsha) over 11 months, and evaluated ADO stability under different storage conditions (4 °C, 20 °C, and 40 °C). ADO levels demonstrated significant seasonal variability, peaking in July-August. Median concentrations increased by 111-189% in warmer months compared to winter across all sites. Storage experiments showed that ADO was most stable at 4 °C (fluctuations < 5% over 7 days), while levels at 40 °C increased by 18%. Re-adjusting the ADO reference range based on seasonal data reduced false positive rates from 2.48% to 0.15%, a 94% reduction. This study underscores the necessity of implementing seasonally dynamic reference ranges and strict cold-chain storage (4 °C) to enhance screening accuracy for ADA deficiency. The findings provide a robust foundation for optimizing neonatal screening protocols globally, especially in regions with distinct seasonal climates.

Newborn screening (NBS) for inherited metabolic diseases (IMD) aims to find children in which immediate action can prevent severe symptoms. We previously studied parental satisfaction with the communication of the NBS result for phenylketonuria, which in the Netherlands is done by the general practitioners (GPs). More than half of all parents were unsatisfied with the communication of the abnormal NBS result. The aim of this qualitative exploratory study was to portray a number of GPs' opinions and experiences in communicating an abnormal metabolic NBS result. We performed semi-structured interviews with ten GPs to evaluate the process of communicating the abnormal NBS result. An additional two GPs provided their answers via email. The data revealed four key themes: (1) dealing with the urgency of the metabolic NBS result, (2) the role of the GP in the NBS process, (3) the current organization of NBS in the Netherlands and (4) evaluating roles and responsibilities in communicating abnormal metabolic NBS results. Despite the willingness of GPs to inform parents about NBS results, it is questionable whether they have the necessary tools to effectively conduct these conversations given their limited experience with IMDs. In light of the increasing number of diseases in the NBS program, it would be interesting to explore alternative tools for communicating the NBS result to parents.

Congenital portosystemic shunts (CPSSs) are often associated with life-threatening systemic complications, which may be detected by identifying hypergalactosemia in newborn screening (NBS). However, diagnosing CPSS at an early stage is not easy. The purpose of this study was to predict CPSS early using screening values and general blood tests. The medical records of 153 patients with hypergalactosemia who underwent NBS in Saitama Prefecture between 1 December 1997 and 31 October 2023 were retrospectively analyzed. We provided the final diagnosis of the analyzed patients. Of the 153 patients, 44 (29%) were in the CPSS group and 83 (54%) were in the transient galactosemia group. Using the initial screening items and the six blood test items, we attempted to extract a CPSS group from the transient galactosemia group. Finally, a model for CPSS prediction was established. From multiple logistic regression analysis, filtered blood galactose-1 phosphate/galactose, serum total bile acid, and ammonia were adopted as explanatory variables for the prediction model. If the cut-off value for predicted disease probability value (P) was >0.357, CPSS was identified with 86.4% sensitivity (95%CI 72.6-94.8%) and 81.9% specificity (95%CI 72.0-89.5%). This predictive model might allow prediction of CPSS and early intervention.

Pyridoxine-dependent epilepsy (PDE) represents a group of rare developmental and epileptic encephalopathies. The most common PDE is caused by biallelic pathogenic variants in ALDH7A1 (PDE-ALDH7A1; OMIM #266100), which encodes α-aminoadipate semialdehyde (α-AASA) dehydrogenase, a key enzyme in lysine catabolism. Affected individuals present with seizures unresponsive to conventional anticonvulsant medications but responsive to high-dose of pyridoxine (vitamin B6). Adjunctive lysine restriction and arginine supplementation have also shown potential in improving neurodevelopmental outcomes. Given the significant benefit of early intervention, PDE-ALDH7A1 is a strong candidate for newborn screening (NBS). However, traditional biomarkers are biochemically unstable at room temperature (α-AASA and piperideine-6-carboxylate) or lack sufficient specificity (pipecolate), limiting their utility for biomarker-based NBS. The recent identification of two novel and stable biomarkers, 2S,6S-/2S,6R-oxopropylpiperidine-2-carboxylate (2-OPP) and 6-oxo-pipecolate (oxo-PIP), offers renewed potential for biochemical NBS. We evaluated the feasibility of incorporating 2-OPP, oxo-PIP, and pipecolate into routine butylated FIA-MS/MS workflows used for biochemical NBS. A total of 9402 dried blood spots (DBS), including nine confirmed PDE-ALDH7A1 patients and 9393 anonymized controls were analyzed using a single multiplex assay. 2-OPP emerged as the most sensitive biomarker, identifying all PDE-ALDH7A1 patients with 100% sensitivity and a positive predictive value (PPV) of 18.4% using a threshold above the 99.5th percentile. Combining elevated 2-OPP (above the 99.5th percentile) with either pipecolate or oxo-PIP (above the 85.0th percentile) as secondary marker detected within the same multiplex FIA-MS/MS assay further improved the PPVs to 60% and 45%, respectively, while maintaining compatibility with butanol-derivatized method. Notably, increasing the 2-OPP threshold above the 99.89th percentile, in combination with either pipecolate or oxo-PIP above the 85.0th percentile resulted in both 100% sensitivity and 100% PPV. This study supports the strong potential of 2-OPP-based neonatal screening for PDE-ALDH7A1 within existing NBS infrastructures. The ability to multiplex 2-OPP, pipecolate and oxo-PIP within a single assay offers a robust, practical, high-throughput and cost-effective approach. These results support the inclusion of PDE-ALDH7A1 in existing biochemical NBS panels. Further prospective studies in larger cohorts are needed to refine cutoffs and confirm clinical performance.

An unintended consequence of cystic fibrosis (CF) newborn screening (NBS) is the identification of infants with a positive NBS who do not meet the diagnostic criteria for CF (two CF-causing variants and/or sweat chloride > 60 mmol/L). This indeterminate diagnosis is called cystic fibrosis transmembrane conductance regulator (CFTR)-related metabolic syndrome (CRMS) or CF screen positive, inconclusive diagnosis (CFSPID). CRMS/CFSPID occurs when it is not clearly known whether CFTR variants are disease-causing. In 2024, the CFTR2 classification of many CFTR variants was changed from unknown significance to either CF-causing variants or variants of varying clinical consequences (VVCCs). We conducted a meta-analysis of CRMS/CFSPID cases from manuscripts to describe how the diagnoses would change using two different variant panels: (1) only CF-causing CFTR variants (Panel_CF-causing) and (2) CF-causing variants and VVCCs (Panel_{CF-causing+VVCCs}). Using the Panel_CF-causing, 8.7% had two CF-causing variants (reclassified as CF), while 91.3% had less than two CF-causing variants (reclassified as Undetected). Using the Panel_{CF-causing+VVCCs}, 51.4% had either two VVCCs or one VVCC with one CF-causing variant detected (reclassified as CRMS/CFSPD), 39.9% had less than two CF-causing variants detected (reclassified as Undetected), and 8.7% had two CF-causing variants (reclassified as CF). In conclusion, using the updated CFTR2 classification of CFTR variants significantly decreases the number of children with CRMS/CFSPID and gives a definitive diagnosis of CF to some children while not detecting as many children who are unlikely to develop CF.

Congenital hypothyroidism (CH) is a leading preventable cause of neurocognitive impairment. Its incidence appears to be rising in several countries. We analysed 27 years of newborn-screening data (1997-2023) from the largest Chilean screening centre, covering 3,225,216 newborns (51.1% of national births), to characterise temporal trends and potential drivers of CH incidence. Annual CH incidence was modelled with Prais-Winsten regression to correct for first-order autocorrelation; additional models assessed trends in gestational age, sex, biochemical markers, and aetiological subtypes. We identified 1550 CH cases, giving a mean incidence of 4.9 per 10,000 live births and a significant yearly increase of 0.067 per 10,000 (95 % CI 0.037-0.098; p < 0.001). Mild cases (confirmation TSH < 20 mU/L) rose (+0.89 percentage points per year; p = 0.002). The program's recall was low (0.05%). Over time, screening and diagnostic TSH values declined, total and free T4 concentrations rose, gestational age at diagnosis fell, and a shift from thyroid ectopy toward hypoplasia emerged; no regional differences were detected. The sustained increase in CH incidence, alongside falling TSH thresholds and growing detection of in situ glands, suggests enhanced recognition of milder disease. Ongoing surveillance should integrate environmental, iodine-nutrition, and genetic factors to clarify the causes of this trend.

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