Search Results (147)

Pompe disease is an autosomal recessive metabolic disorder caused by acid alpha-glucosidase (GAA) deficiency. The use of umbilical cord blood (UCB) for newborn screening (NBS) of Pompe disease, compared to heel-prick sampling, has not been widely studied. This study compared GAA activity in UCB from term newborns with peripheral or heel-prick blood samples obtained on days 1, 2, and 3 after birth. Enzyme assays were performed using UPLC-MS/MS. Sanger sequencing was conducted in infants with low GAA activity to identify pathogenic variants. Among 4091 UCB samples analyzed over 18 months, the mean GAA activity was 10.04 ± 5.95 μM/h, higher in females than males [Median (IQR): 9.83 (5.45) vs. 9.08 (4.97) μM/h, respectively, p < 0.001], and similar across ethnicities. GAA levels in UCB and Day 3 heel-prick samples were comparable. A GAA cut-off value of 1.54 μM/h (0.1% of study population) identified one infant (0.024% prevalence) with a novel bi-allelic variant—c.2005_2010del (p.Pro669_Phe670del) and c.1123C>T (p.Arg375Cys), and 12 infants with non-pathogenic pseudodeficiency alleles. This study supports GAA measurement in UCB as a viable alternative for NBS, with enzyme activity remaining stable for up to 72 h post-collection. Larger-scale multicenter nationwide studies are warranted to confirm this prevalence in our population. Full article

Background/Objectives: Pompe disease (PD) is a rare autosomal recessive disorder caused by a deficiency of the lysosomal acid α-1,4-glucosidase (GAA) encoded by the GAA gene, leading to muscular dysfunctions due to pathological accumulation of glycogen in skeletal and cardiac muscles. PD has been reported in several animals and Japanese quails (JQ; Coturnix japonica), but a causative mutation has yet to be found in JQs with PD. Here, we aimed to identify a pathogenic mutation in JQs associated with PD. Methods: Paraffin-embedded skeletal muscle blocks from four JQs stored since the 1970s were used in this study. After confirming the histopathological phenotypes of PD, Sanger sequencing was performed to identify a pathological mutation in the GAA I gene of JQs. A genotyping survey was conducted using a real-time polymerase chain reaction assay targeting a candidate mutation using DNA samples extracted from 70 new-hatched JQs and 10 eggs from commercial farms. Results: Microscopic analysis confirmed the presence of the PD phenotype in three affected JQs based on abnormal histopathological changes and accumulated glycogen in the affected muscles, while one JQ was unaffected and served as a control. Sanger sequencing revealed that the three affected JQs were homozygous for the deletion of guanine at position 1096 in the open reading frame (c.1096delG). A genotyping survey of 70 JQs and 10 eggs from commercial farms showed that none carried this deletion mutation. Conclusions: This study identified c.1096delG as the pathogenic mutation for PD in JQs. This mutation induces a frameshift and substitution of amino acids at position 366 (alanine to histidine), resulting in premature termination at the 23rd codon (p.A366Hfs*23). This suggests that this mutation causes the deficient activity of GAA in JQs with PD. The identification of the c.1096delG mutation enabled the systematic maintenance of the flock colony in the PD model. Furthermore, this PD model can be used to clarify unknown aspects of PD pathogenesis and develop therapeutic strategies. Full article

Skeletal muscle, constituting ~40% of body mass, serves as a primary effector for movement and a key metabolic regulator through myokine secretion. Hereditary myopathies, including dystrophinopathies (DMD/BMD), limb–girdle muscular dystrophies (LGMD), and metabolic disorders like Pompe disease, arise from pathogenic mutations in structural, metabolic, or ion channel genes, leading to progressive weakness and multi-organ dysfunction. Gene therapy has emerged as a transformative strategy, leveraging viral and non-viral vectors to deliver therapeutic nucleic acids. Adeno-associated virus (AAV) vectors dominate clinical applications due to their efficient transduction of post-mitotic myofibers and sustained transgene expression. Innovations in AAV engineering, such as capsid modification (chemical conjugation, rational design, directed evolution), self-complementary genomes, and tissue-specific promoters (e.g., MHCK7), enhance muscle tropism while mitigating immunogenicity and off-target effects. Non-viral vectors (liposomes, polymers, exosomes) offer advantages in cargo capacity (delivering full-length dystrophin), biocompatibility, and scalable production but face challenges in transduction efficiency and endosomal escape. Clinically, AAV-based therapies (e.g., Elevidys^® for DMD, Zolgensma^® for SMA) demonstrate functional improvements, though immune responses and hepatotoxicity remain concerns. Future directions focus on AI-driven vector design, hybrid systems (AAV–exosomes), and standardized manufacturing to achieve “single-dose, lifelong cure” paradigms for muscular disorders. Full article

Background/Objectives: Glycogen storage disease type II, also known as Pompe disease (PD), is a rare autosomal recessive genetic disorder triggered by a deficiency in lysosomal acid α-glucosidase (GAA). Recently, we discovered two deleterious missense variants of the GAA gene, c.1799G>A (p.Arg600His) (a pathogenic mutation) and c.55G>A (p.Val19Met), in a domestic short-haired cat with PD. This study aimed to design genotyping assays for these two variants and ascertain their allele frequencies in Japanese cat populations. Methods: We developed fluorescent probe-based real-time polymerase chain reaction assays to genotype the c.1799G>A and c.55G>A variants. A total of 738 cats, comprising 99 purebred cats from 20 breeds and 540 mixed-breed cats, were screened using these assays. Results: Genotyping assays clearly differentiated all known genotypes of the two variants. None of the 738 cats tested carried the c.1799G>A variant. However, we identified cats with c.55G/A and c.55A/A genotypes in the purebred (A allele frequency: 0.081) and mixed-breed cats (0.473). A significant difference (p < 0.001) was observed in the A allele frequency between the two groups. Conclusions: The c.1799G>A mutation appears rare in cat populations, suggesting it may be confined to specific pedigree Japanese mixed-breed cats. The c.55G>A variant was detected in purebred and mixed-breed cats, suggesting that it may not be directly linked to feline PD. However, additional studies are required to elucidate the precise relationship between this variant and cardiac function. Genotyping assays will serve as valuable tools for diagnosing and genotyping feline PD. Full article

Pompe disease is a rare autosomal-recessive neuromuscular disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA), leading to the pathological accumulation of glycogen and impaired autophagy. Enzyme replacement therapy (ERT) with recombinant human alpha-glucosidase (rhGAA) has been available since 2006, but may lead to the formation of anti-drug antibodies (ADAs) against the recombinant human enzyme, which, in turn, may adversely affect the response to ERT. Knowledge of the antigenic determinants of rhGAA involved in interaction with ADAs may facilitate the development of strategies to attenuate the anti-drug immune response in patients. Here, we determined the rhGAA ADA epitopes in the plasma of Pompe disease patients using a series of affinity purifications combined with epitope extraction and label free quantitation LC-MS. Full article

Newborn screening laboratories are increasingly adding lysosomal storage disorders (LSDs), such as Mucopolysaccharidosis I (MPS I) and Pompe disease, to their screening panels. Without newborn screening, LSDs are frequently diagnosed only after the onset of symptoms; late detection can lead to profound and irreversible organ damage and mortality. While screening of these disorders has accelerated over the past five years, there is little published information regarding the potential correlation of demographic variables (age at sample collection, birthweight, gestational age, gender, etc.) with lysosomal enzyme activity. The Missouri State Public Health Laboratory prospectively screened more than 475,000 newborns for MPS I, Pompe disease, Gaucher disease, and Fabry disease between 15 January 2013 and 15 May 2018. This report investigates trends between several demographic variables and activities of four lysosomal enzymes: α-L-iduronidase (IDUA), acid α-glucosidase (GAA), acid β-glucocerebrosidase (GBA), and acid α-galactosidase (GLA). This information provides a valuable resource to newborn screening laboratories for the implementation of screening for lysosomal storage disorders and the establishment of screening cutoffs. Full article

Newborn screening (NBS) is leading to the diagnosis of a large number of children with late-onset Pompe disease (LOPD), yet many remain asymptomatic until later years. A high-protein, low-carbohydrate diet is recommended for adults with LOPD. Nutrition guidelines are not available for young children. Methods: 37 children with LOPD aged 1–6 years participated. Early diet history, feeding practices, and 24 h dietary intake were collected via questionnaire. Anthropometric measurements, blood creatine kinase (CK), blood urea nitrogen (BUN)/creatinine ratio, and urine glucose tetrasaccharide (Glc4) were collected at clinic visits. A subset of 19 children received a clinical feeding assessment (CFA). Results: All patients derived their nutrition orally. Breastfeeding was successfully initiated in 73% of infants. Body weight ranged between 3 and 99% and height ranged from 4 to 97%. A tendency to be overweight and obese was noted in older children with LOPD. A total of 24% of the children who had CFA were diagnosed with dysphagia that was typically mild in severity and rarely affected their ability to eat a normal diet. Limiting added sugar and processed foods was the most widely used dietary practice followed by encouraging protein. Protein intake was three–four times higher than the recommended dietary intake (RDA). A high BUN/creatinine ratio was observed in some children, which may indicate incompatibility with protein intake and need for individualizing the diet. Conclusions: The results of this study provide a framework for developing future nutrition guidelines for children with LOPD by performing an individualized assessment of dietary intake, growth, feeding/swallowing, and laboratory parameters. Full article

Background: Lysosomal storage disorders (LSDs) are rare inherited metabolic diseases characterized by defects in lysosomal enzyme function or membrane transport. These defects lead to substrate accumulation and multisystemic manifestations. This review focuses on gastrointestinal (GI) involvement in LSDs, which is a significant but often overlooked aspect of these disorders. Methods: A comprehensive literature review was conducted to examine the pathophysiology, clinical presentation, diagnosis and management of GI manifestations in several LSDs, including Fabry disease, Gaucher disease, Pompe disease, Niemann–Pick disease type C, mucopolysaccharidoses and Wolman disease. Results: The pathogenesis of GI involvement in LSDs varies and encompasses substrate accumulation in enterocytes, mesenteric lymphadenopathy, mass effects, smooth muscle dysfunction, vasculopathy, neuropathy, inflammation and alterations to the microbiota. Clinical presentations range from non-specific symptoms, such as abdominal pain, diarrhea and malabsorption, to more severe complications, such as protein-losing enteropathy and inflammatory bowel disease. Diagnosis often requires a high level of suspicion, as GI symptoms may precede the diagnosis of the underlying LSD or be misattributed to more common conditions. Management strategies include disease-specific treatments, such as enzyme replacement therapy or substrate reduction therapy, as well as supportive care and targeted interventions for specific GI complications. Conclusions: This review highlights the importance of recognizing and properly managing GI manifestations in LSDs to improve patient outcomes and quality of life. It also emphasizes the need for further research to develop more effective treatments for life-threatening GI complications associated with these rare genetic disorders. Full article

Background: Multiplex Ligation Probe Amplification (MLPA) is a widely used technique for the diagnosis of lysosomal storage diseases (LSDs). It analyses over 40 DNA sequences in a single reaction, identifying copy number variations and large deletions/insertions in genes. The diagnostic process in LSDs starts with analysis of the missing or reduced enzyme, followed by genetic investigation and, if possible, a search for accumulated substrates. However, while genetic analysis using Sanger sequencing is excellent at detecting small genetic variations such as single-nucleotide variants (SNVs) and small insertions or deletions, it cannot detect large deletions or insertions. Methods: In the present study, a total of 800 patients with clinical suspicion of Fabry, Gaucher, or Pompe diseases were investigated. An enzyme assay was carried out on each patient, followed by genetic analysis using PCR, Sanger sequencing, and MLPA. Results: Nine patients with deficient or absent enzyme activity had Sanger sequencing results that could not confirm the molecular genetic diagnosis because either no mutation (Fabry) or only one mutation (Gaucher and Pompe) was identified. Subsequent analysis by MLPA identified two males with a hemizygous deletion and two females with a heterozygous deletion for FD. For PD, one female and two males had a heterozygous deletion. For GD, one male had a homozygous deletion and one female had a heterozygous deletion. The remaining patients were analyzed by MLPA with negative results. Conclusions: The results obtained suggest that MLPA should be used in combination with classical sequencing methods to ensure a correct and timely diagnosis of LSDs. Full article

Pennsylvania started newborn screening for Pompe disease (PD) in 2016. As a result, the prevalence of PD has increased with early detection, primarily of late-onset Pompe disease (LOPD). No clear guidelines exist regarding if and when to initiate enzyme replacement therapy (ERT) in patients identified through a newborn screen (NBS). To help define the natural history and indications for starting ERT, we present the long-term follow-up data of 45 patients identified through NBS from 2016 to 2021. These patients were evaluated at regular intervals through our multi-disciplinary clinic at the Children’s Hospital of Philadelphia (CHOP) with physical examinations, physical therapy evaluations, muscle biomarkers including creatine kinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hexosaminidase 4 levels (Hex4), as well as cardiac evaluation at certain points in time. We found that newborn screening of acid alpha-glucosidase (GAA) enzyme detected primarily LOPD. One case of infantile-onset PD (IOPD) was detected. Muscle biomarkers in LOPD were elevated at birth and showed a general downward trend over time. NBS GAA levels and initial CK levels helped to differentiate LOPD cases from unaffected infants (carriers, pseudodeficiency alleles), while Hex4 was not a meaningful discriminator. On repeat NBS, there was a significant difference between mean GAA levels for the unaffected vs. compound heterozygote groups and unaffected vs. homozygote groups for the common splice site pathogenic variant (c.-32-13T>G). Echocardiogram and electrocardiogram (EKG) are essentially normal at the first evaluation in LOPD. One LOPD patient was started on ERT at age 4.5 months. Continued data collection on these patients is critical for developing management guidelines, including timing of ERT and improved genotype–phenotype correlation. Full article

Pompe disease is a neuromuscular disorder caused by a deficiency of the enzyme acid alpha-glucosidase (GAA), which leads to lysosomal glycogen accumulation and progressive development of muscle weakness. Two distinct isoforms have been identified. In the infantile form, the weakness is often severe and leads to motor difficulties from the first few months of life. In adult patients, the progression is slower but can still lead to significant loss of mobility. The current inherent difficulties of the disease lie in both early diagnosis and the use of biomarkers. Given that this is a multifactorial disease, a number of components may exert an influence on the disease process; from the degree of pre-ERT (enzyme replacement therapy) muscle damage to the damaged autophagic system and the different pathways involved. What methodology should be employed to study the complex characteristics of Pompe disease? Our approach relies on the application of genetic and epigenetic knowledge, with a progression from proteomics to transcriptomics. It is also becoming increasingly evident that artificial intelligence is a significant area of interest. The objective of this study is to conduct a comprehensive review of the existing literature on the known data and complications associated with the disease in patients with disorders attributed to Pompe disease. Full article

An intriguing aspect of restrictive cardiomyopathies (RCM) is the microbiome role in the natural history of the disease. These cardiomyopathies are often difficult to diagnose and so result in significant morbidity and mortality. The human microbiome, composed of billions of microorganisms, influences various physiological and pathological processes, including cardiovascular health. Studies have shown that gut dysbiosis, an imbalance in the composition of intestinal bacteria, can contribute to systemic inflammation, a key factor in many cardiovascular conditions. An increase in gut permeability, frequently caused by dysbiosis, allows bacterial endotoxins to enter the bloodstream, activating inflammatory pathways that exacerbate cardiac dysfunction. Recent reports highlight the potential role of microbiome in amyloidogenesis, as certain bacteria produce proteins that accelerate the formation of amyloid fibrils. Concurrently, advancements in amyloidosis treatments have sparked renewed hopes, marking a promising era for managing these kinds of diseases. These findings suggest that the gut–heart axis may be a potential factor in the development and progression of cardiovascular disease like RCM, opening new paths for therapeutic intervention. The aim of this review is to provide a detailed overview of the gut–heart axis, focusing on RCM. Full article

Newborn screening (NBS) presents an opportunity to identify a subset of babies at birth who are at risk for developmental delays and could benefit from a range of developmental services. Potential developmental services in the United States include Part C Early Intervention (EI), private therapies, and school-based services. Using parent-reported outcomes, this study examined the rates at which a sample of children diagnosed with NBS conditions used each developmental service. An online survey of 153 parents representing children with 27 different NBS conditions found that nearly 75% of children (n = 112) used at least one developmental service, with private therapies being the most frequent. Children were referred to EI relatively early and were often eligible because their medical diagnosis automatically qualified them. When examining condition-specific results for children with severe combined immunodeficiencies, congenital hypothyroidism, and Pompe disease, we found variability in rates of use, with high rates overall. Our findings suggest that many children diagnosed with an NBS condition continue to have developmental delays even after they receive appropriate medical care. Future research with more systematic follow-up is needed to understand whether the NBS program facilitates entry into these services and whether more streamlined processes could benefit children and families. Full article

Myocardial ischaemia is a decompensation of the oxygen supply and demand ratio, often caused by coronary atherosclerosis. During the initial stage of ischaemia, the electrical activity of the heart is disrupted, increasing the risk of malignant arrhythmias. The aim of this study is to understand the differential behaviour of the ECG during occlusion of both the left anterior descending (LAD) and right anterior coronary artery (RCA), respectively, using spatio-temporal quantifiers from information theory. A standard 12-lead ECG was recorded for each patient in the database. The control condition was obtained initially. Then, a percutaneous transluminal coronary angioplasty procedure (PTCA), which encompassed the occlusion/reperfusion period, was performed. To evaluate information quantifiers, the Bandt and Pompe permutation method was used to estimate the probability distribution associated with the electrocardiographic vector modulus. Subsequently, we analysed the positioning in the $\mathcal{H}\times \mathcal{C}$ causal plane for the control and ischaemia. In LAD occlusion, decreased entropy and increased complexity can be seen, i.e., the behaviour is more predictable with an increase in the degree of complexity of the system. RCA occlusion had the opposite effects, i.e., the phenomenon is less predictable and exhibits a lower degree of organisation. Finally, both entropy and complexity decrease during the reperfusion phase in LAD and RCA cases. Full article

For years, the treatment of many cardiomyopathies has been solely focused on symptom management. However, cardiomyopathies have a genetic substrate, and directing therapy towards the pathophysiology rather than the epiphenomenon of the disease may be a winning strategy. Gene therapy involves the insertion of genes or the modification of existing ones and their regulatory elements through strategies like gene replacement and gene editing. Recently, gene therapy for cardiac amyloidosis and Duchenne muscular dystrophy has received approval, and important clinical trials are currently evaluating gene therapy methods for rare heart diseases like Friedreich’s Ataxia, Danon disease, Fabry disease, and Pompe Disease. Furthermore, favorable results have been noted in animal studies receiving gene therapy for hypertrophic, dilated, and arrhythmogenic cardiomyopathy. This review discusses gene therapy methods, ongoing clinical trials, and future goals in this area. Full article