The future of newborn screening for lysosomal disorders

Newborn Screening for Acid Sphingomyelinase Deficiency: Prevalence and Genotypic Findings in Italy

Acid sphingomyelinase deficiency (ASMD) is a rare lysosomal storage disorder with a broad clinical spectrum. Early diagnosis and initiation of treatment are crucial for improving outcomes, yet the disease often goes undiagnosed due to its rarity and phenotypic heterogeneity. This study aims to evaluate the feasibility and disease incidence of newborn screening (NBS) for ASMD in Italy. Dried blood spot samples from 275,011 newborns were collected between 2015 and 2024 at the Regional Center for Expanded NBS in Padua. Acid sphingomyelinase activity was assayed using tandem mass spectrometry. Deidentified samples with reduced enzyme activity underwent second-tier testing with LysoSM quantification and SMPD1 gene analysis. Two samples were identified with reduced sphingomyelinase activity and elevated LysoSM levels. Both carried two SMPD1 variants, suggesting a diagnosis of ASMD. Molecular findings included novel and previously reported variants, some of uncertain significance. The overall incidence was 1 in 137,506 newborns and the PPV was 100%. This study demonstrates the feasibility of NBS for ASMD in Italy and provides evidence of a higher disease incidence than clinically reported, suggesting ASMD is an underdiagnosed condition. Optimized screening algorithms and second-tier biomarker testing can enhance the accuracy of NBS for ASMD. The long-term follow-up of identified cases is necessary for genotype-phenotype correlation and improving patient management.

Navigating Pompe Disease Assessment: A Comprehensive Scoping Review

Pompe disease (PD) is a rare progressive autosomal recessive disorder resulting from the deficiency of acid alpha-glucosidase (GAA) enzyme activity. Due to its multisystemic involvement, PD leads to significant morbidity and impacts patients' quality of life. Despite the availability of approved disease-modifying treatments, the prompt diagnosis and management of PD, which are crucial for patient outcomes, still present several challenges. This scoping review aimed to synthesize the evidence regarding methods for screening, diagnosing, and following up PD. We searched articles in English and Spanish published from 2017 to February 8, 2022, across 11 databases (i.e., Cochrane Database of Systematic Reviews, Directory of Open Access Journals (DOAJ), Epistemonikos, Ingenta Connect, Medline/PubMed, SAGE, SciELO Citation Index, ScienceDirect, Springer Link, Virtual Health Library, and Wiley Online Library). We included primary studies (i.e., case reports, case series, cross-sectional studies, case controls, cohorts, clinical trials, and qualitative studies), reviews, and guidelines that described at least one assessment method for patients with confirmed clinical, genetic, or biochemical PD. Two independent reviewers screened and extracted data from articles, with a third reviewer solving conflicts. We synthesized data with narrative summaries and descriptive statistics. After screening 2,139 titles and abstracts, we included 96 eligible articles. Cross-sectional studies (n = 30) and guidelines (n = 1) were the most and least prevalent designs, respectively. Most studies targeted late-onset PD (LOPD, n = 48) and infantile-onset PD (IOPD, n = 21). Eleven articles described newborn screening programs, highlighting their potential to improve PD prevalence estimations and still limited availability among countries. Overall, 81 articles documented clinical manifestations of PD. Hypotonia (n = 7) and hypertrophic cardiomyopathy (n = 7) were the most documented for IOPD, while progressive muscle weakness (n = 21) and dyspnea (n = 11) were the most prevalent for LOPD. We found 26 articles reporting biochemical assays, with dried blood spots (DBS) for GAA enzyme deficiency detection being the most cited (n = 19). We also noted a lack of standardization in documenting DBS results. Additionally, 21 articles mentioned genetic studies, with next-generation sequencing emerging as the gold standard for identifying mutated alleles. Functional studies were the most utilized to follow up with patients. However, monitoring strategies for pediatric and adult PD lacked consensus, and only one article assessed patients' quality of life. This review comprehensively evaluated the literature on PD screening, diagnosis, and follow-up methods, identifying prevalent techniques within each assessment category. We emphasized the need for a more standardized approach to reporting biochemical assays, genetic testing, and clinical presentations. Our review also underscored the critical lack of standardization in PD follow-up. Addressing these gaps will enhance the comparability of future research findings and improve the quality of PD-related healthcare. Limitations of this review included restricting eligible languages and publication years to the latest five, the methodological heterogeneity of selected articles, and the lack of individual study bias assessment.

Newborn Screening of 6 Lysosomal Storage Disorders by Tandem Mass Spectrometry

This study was designed to screen 6 lysosomal storage diseases (LSDs) in neonates using tandem mass spectrometry (MS/MS), and establish cutoff values for these LSDs with 3000 dried blood spots (DBS) samples. Cutoff values for α-L-iduronidase (IDUA), α-galactosidase (GLA), acid beta glucosidase (ABG), β-galactocerebrosidase (GALC), acid sphingomyelinase (ASM), and acid alpha glucosidase (GAA) were as follows: GLA, > 2.06 μmol/L·h; ABG, > 1.78 μmol/L·h; ASM, > 0.99 μmol/L·h; IDUA, > 1.33 μmol/L·h; GALC, > 0.84 μmol/L·h; and GAA, > 2.06 μmol/L·h. There were 30 positives in initial MS/MS screening test, and 15 samples were still positive with repeat testing. Their parents/guardians were recontacted and DBS samples were collected again for test. Only 1 child showed abnormal GAA enzyme activity after recontacting process, and was diagnosed with Pompe disease after genetic screening. Eventually, cutoff values of 6 specific enzyme activities were established and MS/MS is effective for early LSDs screening.

Optimization of systemic AAV9 gene therapy in Niemann-Pick disease type C1 mice

Niemann-Pick disease, type C1 (NPC1) is a rare, fatal neurodegenerative disorder caused by pathological variants in NPC1, which encodes a lysosomal cholesterol transport protein. There are no FDA approved treatments for this disorder. Both systemic and central nervous system delivery of AAV9-hNPC1 have shown significant disease amelioration in NPC1 murine models. To assess the impact of dose and window of therapeutic efficacy in Npc1 m1N mice, we systemically administered three different doses of AAV9-hNPC1 at 4 weeks old and the medium dose at pre-, early, and post-symptomatic timepoints. Higher vector doses and treatment earlier in life were associated with enhanced transduction in the nervous system and resulted in significantly increased lifespan. Similar beneficial effects were noted after gene therapy in Npc1 I1061T mice, a model that recapitulates a common human hypomorphic variant. Our findings help define dose ranges, treatment ages, and efficacy in severe and hypomorphic models of NPC1 deficiency and suggest that earlier delivery of AAV9-hNPC1 in a pre-symptomatic disease state is likely to yield optimal outcomes in individuals with NPC1.

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Gene therapies for mucopolysaccharidoses

Current specific treatments for mucopolysaccharidoses (MPSs) include enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT). Both treatments are hampered by several limitations, including lack of efficacy on brain and skeletal manifestations, need for lifelong injections, and high costs. Therefore, more effective treatments are needed. Gene therapy in MPSs is aimed at obtaining high levels of the therapeutic enzyme in multiple tissues either by engrafted gene-modified hematopoietic stem progenitor cells (ex vivo) or by direct infusion of a viral vector expressing the therapeutic gene (in vivo). This review focuses on the most recent clinical progress in gene therapies for MPSs. The various gene therapy approaches with their strengths and limitations are discussed.

Analysis of Metabolic Changes in Endogenous Metabolites and Diagnostic Biomarkers for Various Diseases Using Liquid Chromatography and Mass Spectrometry

Analysis of endogenous metabolites in various diseases is useful for searching diagnostic biomarkers and elucidating the molecular mechanisms of pathophysiology. The author and collaborators have developed some LC/tandem mass spectrometry (LC/MS/MS) methods for metabolites and applied them to disease-related samples. First, we identified urinary conjugated cholesterol metabolites and serum N-palmitoyl-O-phosphocholine serine as useful biomarkers for Niemann-Pick disease type C (NPC). For the purpose of intraoperative diagnosis of glioma patients, we developed the LC/MS/MS analysis methods for 2-hydroxyglutaric acid or cystine and found that they could be good differential biomarkers. For renal cell carcinoma, we searched for various biomarkers for early diagnosis, malignancy evaluation and recurrence prediction by global metabolome analysis and targeted LC/MS/MS analysis. In pathological analysis, we developed a simultaneous LC/MS/MS analysis method for 13 steroid hormones and applied it to NPC cells, we found 6 types of reductions in NPC model cells. For non-alcoholic steatohepatitis (NASH), model mice were prepared with special diet and plasma bile acids were measured, and as a result, hydrophilic bile acids were significantly increased. In addition, we developed an LC/MS/MS method for 17 sterols and analyzed liver cholesterol metabolites and found a decrease in phytosterols and cholesterol synthetic markers and an increase in non-enzymatic oxidative sterols in the pre-onset stage of NASH. We will continue to challenge themselves to add value to clinical practice based on cutting-edge analytical chemistry methodology.

[Development of analytics in newborn screening-from the Guthrie card to genetics]

For more than five decades, all newborns in Germany have been offered a screening examination for the early detection of congenital treatable diseases. Since its inception, about 35 million children have been screened in this way.Originally, screening exams only included early detection of phenylketonuria, which, without timely treatment, would lead to mental retardation that could no longer be corrected. The bacteriological Guthrie test allowed the detection of elevated concentrations of phenylalanine. The methods used today are the result of decades of development. They have been expanded to include tests to determine enzyme activities, immunoassays for the early detection of important hormonal disorders such as congenital hypothyroidism, and high-pressure liquid chromatography for the diagnosis of pathologic hemoglobins. The very sophisticated tandem mass spectrometry enables the simultaneous detection of amino acid and fatty acid compounds. Steroids can also be identified. The specificity can be further increased by combining tandem mass spectrometry with chromatographic pre-separation. In recent years, chemical-analytical analyses have been supplemented by genetic diagnostic methods such as quantitative or qualitative polymerase chain reaction (PCR).The current state of laboratory technology is by no means final. Both classical analytics and especially genetic methods are facing further rapid development. Although the expansion of screening is also a consequence of technical development, the inclusion of further congenital diseases is fundamentally dependent on the given therapy. But it is precisely here that many innovations are currently being investigated. Gene therapy is at the forefront of interest.

Newborn screening for the full set of mucopolysaccharidoses in dried blood spots based on first-tier enzymatic assay followed by second-tier analysis of glycosaminoglycans

Newborn screening (NBS) for the full set of mucopolysaccharidoses (MPSs) is now possible by either measuring all of the relevant enzymatic activities in dried blood spots (DBS) using tandem mass spectrometry followed by measurement of accumulated glycosaminoglycans (GAGs) or the vice-versa approach. In this study we considered multiple factors in detail including reagent costs, time per analysis, false positive rates, instrumentation requirements, and multiplexing capability. Both NBS approaches are found to provide acceptable solutions for comprehensive MPS NBS, but the enzyme-first approach allows for better multiplexing to include numerous additional diseases that are appropriate for NBS expansion. By using a two-tier NBS approach, the false positive and false negatives rates are expected to acceptably low and close to zero.

CD8+ T cell depletion prevents neuropathology in a mouse model of globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD) or Krabbe's disease is a fatal genetic demyelinating disease of the central nervous system caused by loss-of-function mutations in the galactosylceramidase (galc) gene. While the metabolic basis for disease is known, the understanding of how this results in neuropathology is not well understood. Herein, we report that the rapid and protracted elevation of CD8+ cytotoxic T lymphocytes occurs coincident with clinical disease in a mouse model of GLD. Administration of a function-blocking antibody against CD8α effectively prevented disease onset, reduced morbidity and mortality, and prevented CNS demyelination in mice. These data indicate that subsequent to the genetic cause of disease, neuropathology is driven by pathogenic CD8+ T cells, thus offering novel therapeutic potential for treatment of GLD.

Omics-Based Approaches for the Characterization of Pompe Disease Metabolic Phenotypes

Lysosomal storage disorders (LSDs) constitute a large group of rare, multisystemic, inherited disorders of metabolism, characterized by defects in lysosomal enzymes, accessory proteins, membrane transporters or trafficking proteins. Pompe disease (PD) is produced by mutations in the acid alpha-glucosidase (GAA) lysosomal enzyme. This enzymatic deficiency leads to the aberrant accumulation of glycogen in the lysosome. The onset of symptoms, including a variety of neurological and multiple-organ pathologies, can range from birth to adulthood, and disease severity can vary between individuals. Although very significant advances related to the development of new treatments, and also to the improvement of newborn screening programs and tools for a more accurate diagnosis and follow-up of patients, have occurred over recent years, there exists an unmet need for further understanding the molecular mechanisms underlying the progression of the disease. Also, the reason why currently available treatments lose effectiveness over time in some patients is not completely understood. In this scenario, characterization of the metabolic phenotype is a valuable approach to gain insights into the global impact of lysosomal dysfunction, and its potential correlation with clinical progression and response to therapies. These approaches represent a discovery tool for investigating disease-induced modifications in the complete metabolic profile, including large numbers of metabolites that are simultaneously analyzed, enabling the identification of novel potential biomarkers associated with these conditions. This review aims to highlight the most relevant findings of recently published omics-based studies with a particular focus on describing the clinical potential of the specific metabolic phenotypes associated to different subgroups of PD patients.

High-risk screening for Fabry disease in hemodialysis patients in Chiba Prefecture, Japan

BACKGROUND

High-risk screening for Fabry disease in dialysis patients is an effective means for reducing the number of undiagnosed cases. However, such screening has not been conducted in Chiba Prefecture, Japan. Herein, we aimed to estimate the prevalence of Fabry disease among patients undergoing hemodialysis in Chiba Prefecture by high-risk screening using α-galactosidase A (αGal A) activity measurement, and examine the hemodialysis effect on αGal A activity.

METHODS

Patients who underwent maintenance hemodialysis at 25 facilities in Chiba Prefecture were recruited. The αGal A activity was measured using the dried blood spot (DBS) test as the first screening. If the enzyme activity was lower than the cut-off, the second screening was performed with the same method before and after dialysis.

RESULTS

Overall, 2924 patients (2036 men and 888 women) were included from which 94 cases (45 men and 48 women) showed decreased αGAL activity in the first screening and 3 (two men and one women) in the second screening. Genetic testing was performed in 3 patients, and the c.1078G > A mutation in GLA gene was detected in one male patient (0.03%). There has been a statistically significant decrease in αGal A activity of DBS at post-dialysis compared to that at pre-dialysis (20.5 ± 10.4 pmol/h/disk and 22.7 ± 11.5 pmol/h/disk, p < 0.0001).

CONCLUSION

The prevalence of Fabry disease among patients undergoing hemodialysis in Chiba Prefecture was estimated as 0.03%. This is the first time that dialysis has been shown to affect the αGal A activity.

Scaling genetic resources: New paradigms for diagnosis and treatment of rare genetic disease

Development of genetic tests for rare genetic diseases has traditionally focused on individual diseases. Similarly, development of new therapies occurred one disease at a time. With >10,000 rare genetic diseases, this approach is not feasible. Diagnosis of genetic disorders has already transcended old paradigms as whole exome and genome sequencing have allowed expedient interrogation of all relevant genes in a single test. The growth of newborn screening has allowed identification of diseases in presymptomatic babies. Similarly, the ability to develop therapies is rapidly expanding due to technologies that leverage platform technology that address multiple diseases. However, movement from the basic science laboratory to clinical trials is still hampered by a regulatory system rooted in traditional trial design, requiring a fresh assessment of safe ways to obtain approval for new drugs. Ultimately, the number of nucleic acid-based therapies will challenge the ability of clinics focused on rare diseases to deliver them safely with appropriate evaluation and long-term follow-up. This manuscript summarizes discussions arising from a recent National Institutes of Health conference on nucleic acid therapy, with a focus on scaling technologies for diagnosis of rare disorders and provision of therapies across the age and disease spectrum.

Global Incidence and Prevalence of Gaucher Disease: A Targeted Literature Review

Incidence and prevalence estimates for Gaucher disease (GD) are scarce for this rare disease and can be variable within the same region. This review provides a qualitative synthesis of global GD incidence and prevalence estimates, GD1-3 type-specific and overall, published in the last 10 years. A targeted literature search was conducted across multiple databases from January 2011 to September 2020, including web-based sources and congress proceedings to May 2021. Searches yielded 490 publications, with 31 analyzed: 20 cohort studies (15 prospective, 5 retrospective), 6 cross-sectional studies, 5 online reports (most from Europe (n = 11) or North America (n = 11); one multiregional). Across all GD types, incidence estimates ranged 0.45-25.0/100,000 live births (16 studies), lowest for Asia-Pacific. Incidence of GD1: 0.45-22.9/100,000 live births (Europe and North America) and GD3: 1.36/100,000 live births (Asia-Pacific only). GD type-specific prevalence estimates per 100,000 population were GD1: 0.26-0.63; GD2 and GD3: 0.02-0.08 (Europe only); estimates for GD type unspecified or overall ranged 0.11-139.0/100,000 inhabitants (17 studies), highest for North America. Generalizability was assessed as "adequate"or "intermediate" for all regions with data. GD incidence and prevalence estimates for the last 10 years varied considerably between regions and were poorly documented outside Europe and North America. Data for GD2 and GD3 were limited.

Parental Depression and Anxiety Associated with Newborn Bloodspot Screening for Rare and Variable-Onset Disorders

The ability to screen newborns for a larger number of disorders, including many with variable phenotypes, is prompting debate regarding the psychosocial impact of expanded newborn bloodspot screening (NBS) on parents. This study compares psychological outcomes of parents of children with a range of NBS/diagnostic experiences, with a particular focus on lysosomal storage disorders (LSDs) and X-linked adrenoleukodystrophy (X-ALD) as representative disorders with complex presentations. An online cross-sectional survey with six domains was completed in 2019 by a volunteer sample of parents with at least one child born between 2013 and 2018. Parents were classified in the analysis stage into four groups based on their child's rare disorder and means of diagnosis. Stress and depression were estimated using dichotomous measures of the depression subscale of the Hospital Anxiety and Depression Scale and the Parental Stress Scale. Logistic regression models were estimated for the relationship between the parent group and stress/depression, controlling for demographic variables (region of the US, income, education, major life events, relationship to the child, number of children, parent age, and race/ethnicity). One hundred seventy-four parents were included in this analysis. Parents of children with an LSD or X-ALD diagnosis clinically may have higher odds of depression (OR: 6.06, 95% CI: 1.64-24.96) compared to parents of children with the same disorders identified through NBS, controlling for covariates. Although a similar pattern was observed for parental stress (OR: 2.85, 95% CI: 0.82-10.37), this did not reach statistical significance. Ethically expanding NBS and genome sequencing require an understanding of the impacts of early detection for complex disorders on families. These initial findings are reassuring, and may have implications as NBS expands. Given our small sample size, it is difficult to generalize these findings to all families. These preliminary trends warrant further investigation in larger and more diverse populations.

Newborn screening research sponsored by the NIH: From diagnostic paradigms to precision therapeutics

Newborn screening (NBS) is a successful public health initiative that effectively identifies pre-symptomatic neonates so that treatment can be initiated before the onset of irreversible morbidity and mortality. Legislation passed in 2008 has supported a system of state screening programs, educational resources, and an evidence-based review process to add conditions to a recommended universal newborn screening panel (RUSP). The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), NIH, has promoted NBS research to advance legislative goals by supporting research that will uncover fundamental mechanisms of disease, develop treatments for NBS disorders, and promote pilot studies to test implementation of new conditions. NICHD's partnerships with other federal agencies have contributed to activities that support nominations of new conditions to the RUSP. The NIH's Newborn Sequencing In Genomic Medicine and Public Health (NSIGHT) initiative funded research projects that considered how genomic sequencing could be integrated into NBS and its ethical ramifications. Recently, the workshop, "Gene Targeted Therapies: Early Diagnosis and Equitable Delivery," has explored the possibility of expanding NBS to include genetic diagnosis and precision, gene-based therapies. Although hurdles remain to realize such a vision, broad engagement of multiple stakeholders is essential to advance genomic medicine within NBS.

Multiplex Lysosomal Enzyme Activity Assay on Dried Blood Spots Using Tandem Mass Spectrometry

Deficiencies of the enzymes in lysosomes result in the accumulation of undegraded materials and subsequently cellular dysfunction. Early identification of deficiencies can lead to better clinical outcomes before irreversible organ and tissue damages occur. In this chapter, lysosomal enzymes are extracted from dried blood spots and incubated with the commercialized and multiplexed enzyme cocktail containing corresponding substrates and internal standards. After incubation, the enzymatic reactions are quenched, and the mixtures of the reaction products are prepared using liquid/liquid extractions. Multiple enzymes are quantified simultaneously using selected ion monitoring on liquid chromatography-mass spectrometry (LC-MS/MS) system.

A qualitative assessment of parental experiences with false-positive newborn screening for Krabbe disease

Numerous US states have implemented newborn screening for Krabbe disease (Krabbe NBS) as a result of legislative state mandates. While healthcare provider opinions toward Krabbe NBS have been documented, few studies have explored parental experiences and opinions regarding Krabbe NBS. Eleven families, who received a false-positive Krabbe NBS result and received genetic counseling at an institution in central Ohio, were consented to participate in semistructured interviews. Interviews explored parents' experiences throughout the NBS process and ascertained their opinions regarding Krabbe NBS. Three major themes emerged from thematic analysis: (1) improved understanding of the NBS process from a parent perspective, (2) the role of healthcare provider communication, and (3) the value of Krabbe NBS. Parents saw value in Krabbe NBS, despite many disclosing emotional distress and uncertainty throughout the NBS process. Parent experiences throughout the NBS process varied widely. Due to the expressed emotional distress, further research assessing effective communication during the NBS process is warranted. The researchers suggest additional NBS education for non-genetics healthcare providers (i.e., nurses or primary care physicians) and further participation of genetic counselors in the NBS process may benefit families with a positive Krabbe NBS result.