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Competing Interests: Harrison N. Jones has received research/grant support and honoraria from Sanofi Genzyme Priya S. Kishnani has received research/grant support from Sanofi Genzyme, Valerion Therapeutics, and Amicus Therapeutics; consulting fees and honoraria from Sanofi Genzyme, Amicus Therapeutics, Vertex Pharmaceuticals and Asklepios Biopharmaceutical, Inc. (AskBio); is a member of the Pompe and Gaucher Disease Registry Advisory Board for Sanofi Genzyme, Amicus Therapeutics, and Baebies; and has equity in Actus Therapeutics, which is developing gene therapy for Pompe disease.

Objectives: To evaluate the clinical and molecular spectrum, and factors affecting clinical outcome of patients in India diagnosed with infantile-onset Pompe disease (IOPD).Study Design: In this multicenter, cross-sectional study, we evaluated the records of 77 patients with IOPD to analyze their clinical course, outcomes, and factors influencing the outcomes.Results: Of the 77 patients with IOPD, phenotype data were available in 59; 46 (78%) had the classic phenotype. Overall, 58 of 77 (75%) and 19 of 77 (25%) patients were symptomatic before and after age 6 months, respectively. Alpha-glucosidase gene variant analysis available for 48 patients (96 alleles) showed missense variants in 49 alleles. Cross-reactive immunologic material (CRIM) status could be determined or predicted in 44 of 48 patients. In total, 32 of 44 patients (72%) were CRIM-positive, and 12 of 44 patients (27%) were CRIM-negative. Thirty-nine cases received enzyme-replacement therapy (ERT), alglucosidase alfa, and 38 patients never received ERT. Median age at initiation of ERT was 6.5 months. Response to ERT was better in babies who had CRIM-positive, non-classic IOPD.Conclusions: This study highlights the clinical spectrum of IOPD in India and provides an insight on various factors, such as undernutrition, feeding difficulties, and recurrent respiratory infection, as possible factors influencing clinical outcomes in these patients. The study also reiterates the importance of raising awareness among clinicians about the need for early diagnosis and timely treatment of IOPD. [ABSTRACT FROM AUTHOR]

Infantile-onset Pompe disease (IOPD) is a life-threatening multi-organ disease caused by an inborn defect of lysosomal acid α-glucosidase (GAA), which can degrade glycogen into glucose. Lack of GAA causes abnormal accumulation of glycogen in the lysosomes, particularly in the skeletal muscle, liver, and heart. Enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) is the only available treatment; however, its effect varies by organ. Thus, to fully understand the pathomechanism of IOPD, organ-specific disease models are necessary. We previously generated induced pluripotent stem cells (iPSCs) from three unrelated patients with IOPD and establish a skeletal muscle model of IOPD. Here, we used the same iPSC lines as the previous study and differentiated them into hepatocytes. As a result, hepatocytes differentiated from iPSC of IOPD patients showed abnormal accumulation of lysosomal glycogen, the hallmark of Pompe disease. Using this model, we also demonstrated that glycogen accumulation was dose-dependently restored by rhGAA treatment. In conclusion, we have successfully established an in vitro liver model of IOPD using patient-specific iPSCs. This model can be a platform to elucidate the underlying disease mechanism or to be applied to drug-screening. Moreover, our study also suggest that an iPSC-based approach is suitable for modeling of diseases that affect multiple organs like Pompe disease., (Copyright © 2019 Yoshida, Jonouchi, Osafune, Takita and Sakurai.)

Infantile-onset Pompe disease is a lysosomal storage disorder characterised with hypertrophic cardiomyopathy, respiratory insufficiency, and hypotonia. Dilated cardiomyopathy is an extremely rare and curable complication of nutritional hypocalcaemic rickets. A 3-month-old female infant was referred to our paediatric ICU with a 4-day history of fatigue, tachypnoea, tachycardia, hypoxia, and respiratory failure. According to the laboratory, radiology, and echocardiography findings, she was first diagnosed with nutritional hypocalcaemic rickets-related dilated cardiomyopathy, but vitamin D and elementary calcium supplementation unmasked the underlying infantile-onset Pompe disease. Nutritional hypocalcaemic rickets and infantile-onset Pompe disease must always be kept in mind among the causes of concomitant dilated cardiomyopathy and hypertrophic cardiomyopathy.

Pompe disease is caused by a deficiency of acid α-glucosidase (GAA; EC, 3.2.1.20), and the infantile-onset form is rapidly fatal if left untreated. However, recombinant human GAA (rhGAA) enzyme replacement therapy (ERT) extends survival for infantile Pompe patients. Although cross-reactive immunologic material (CRIM)-negative patients, who lack detectable endogenous GAA, mount an immune response to rhGAA that renders the therapy ineffective, timely induction of immune tolerance in these patients may improve clinical outcomes. Previously, CRIM status has been determined by Western blot analysis in cultured skin fibroblasts, a process that can take a few weeks. We present a blood-based CRIM assay that can yield results within 48 to 72 h. Results from this assay have been confirmed by GAA Western blot analysis in fibroblasts or by GAA sequencing in a small number of Pompe disease patients. Rapid classification of CRIM status will assist in identifying the most effective treatment course and minimizing treatment delays in patients with infantile-onset Pompe disease., (© 2013.)