Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 25 2 2026 02 01 212 221 Solmaz Aziz-Ahari Division of Pediatric Neurology, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Mahdi Aminian Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Aliasghar Rahimian Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Shahriar Nafissi 3 Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Morteza Heidari Division of Pediatric Neurology, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Ali Rabbani Growth and Development Research Center, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Department of Pediatric Endocrinology, Pediatric Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Amir-Hassan Zarnani Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Ali Mohebbi Growth and Development Research Center, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Reza Shervin Badv Division of Pediatric Neurology, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Narges Salajegheh Medical Laboratory, Social Security Organization, Tehran, Iran Sahar Mortezagholi Department of Immunology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Safdar Masoumi Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Zahra Hadipour Department of Clinical Genetics, Atieh Hospital, Tehran, Iran Reza Boostani Department of Neurology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Mehran Beiraghi Toosi Department of Pediatric Neurology, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran Keyhan Sayadpour Zanjani Division of Cardiology, Department of Pediatric, Pediatric Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Ali Khajeh Department of Pediatric Neurology, Children and Adolescents Health Research Center, Zahedan University of Medical Sciences, Zahedan, Iran Seyed Hassan Tonkaboni Department of Pediatric Neurology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maryam Sadeghi Division of Pediatric Neurology, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Farzad Fatehi Department of Neurology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Elahe Vafaei Fetal and Pediatric Cardiovascular Research Center, Pediatric Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran Mahmoud Reza Ashrafi Division of Pediatric Neurology, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Neuromuscular Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Growth and Development Research Center, Pediatrics Center of Excellence, Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran 2025 04 21 2025 08 01 Anti-recombinant human acid α-glucosidase (anti-rhGAA) antibody formation is a major challenge in patients with Pompe disease receiving enzyme replacement therapy (ERT). The clinical significance of these antibodies and their detection methods remain uncertain. This study aimed to evaluate the diagnostic and functional relevance of anti-rhGAA antibodies in late-onset Pompe disease (LOPD) and to compare the performance of ELISA and Western blot assays. Fourteen patients with LOPD undergoing ERT and 14 age- and sex-matched healthy controls were studied. Serum anti-rhGAA antibodies and their IgG, IgM, and IgA isotypes were quantified using ELISA and verified by Western blot. Motor function was assessed using the Pompe Motor Function Levels Questionnaire, an adapted version of the GMFCS validated for Pompe disease. Total and isotype-specific anti-rhGAA antibody levels were significantly higher in patients than in controls. ROC analysis showed excellent discrimination between groups. Strong agreement was observed between ELISA and Western blot results. However, antibody levels were not significantly correlated with motor function grade. Given the small sample size (n = 14), this non-significant result may reflect limited statistical power rather than a true lack of association. Anti-rhGAA antibody detection effectively distinguishes LOPD patients from healthy individuals. Western blot provides a reliable, low-cost alternative to ELISA, particularly useful in resource-limited settings. Nevertheless, the prognostic utility of antibody titers for functional outcomes remains uncertain and warrants larger, multicenter validation studies. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4423 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4423/2264