Uncorrected Proof Iran J Pediatr. In Press(In Press):e111562. Published online 2021 November 19. doi: 10.5812/ijp.111562. Research Article Elosulfase Alfa Treatment in Morquio A Patients in Iran: A Before and After Study Mohammadreza Alaei 1 , Marjan Shakiba 1 , Hedyeh Saneifard 1 , Ghamartaj Khanbabaee 2 , Mohammadreza Khalilian 3 , Asieh Mosallanejad 1 , Saleheh Tajalli 4 and Mojtaba Lotfi 5, * 1 Department of Pediatric Endocrinology and Metabolic Diseases, Mofid Children Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2 Department of Pediatric Pulmonology, Mofid Children’s Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Department of Pediatric Cardiology, Mofid Children Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran 4 Nursing Care Research Center (NCRC), School of Nursing and Midwifery, Iran University of Medical Sciences, Tehran, Iran 5 Department of Pediatric Endocrinology and Metabolism, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran * Corresponding author: Department of Pediatric Endocrinology and Metabolism, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Email: lotfimojtaba1362@gmail.com Received 2020 November 24; Revised 2021 October 23; Accepted 2021 October 24. Abstract Background: Morquio A, an autosomal recessive lysosomal storage disease, is caused by a defect in the enzyme N-acetyl- galactosamine-6-sulfatase. This leads to the accumulation of the glycosaminoglycans chondroitin-6-sulfate (C6S) and keratan sul- fate (KS), resulting in various skeletal manifestations, multisystemic impairments, and significant morbidities. Objectives: This study aimed to evaluate the impact of the addition of elosulfase alfa to the hospital protocol on treating Iranian pediatricians with Morquio A syndrome. Methods: A before and after study was conducted on ten patients with Morquio A syndrome diagnosis from 2019 to 2020. Elosul- fase alfa was prescribed with the standard dose of 2 mg/kg/weekly IV infusion for 54 weeks. Then, growth indices, quality of life, and cardiopulmonary data were collected by research assistants using a pre-designed check. Data were entered in SPSS version 23. Quantitative variables were compared between the two periods using the Student’s t-test, and qualitative variables were compared using the χ 2 test or Fisher’s exact test. Results: Ten pediatricians with MPS IV were included, seven of whom were female, with the mean age of 5.8 ± 2.3 years. The mean- time for walking 6 m (P = 0.005), standing (P = 0.005), the stair climb test (P = 0.007), and quality of life (P = 0.015) had significant statistical difference before and after treatment by elosulfase alfa. Conclusions: The addition of elosulfase alfa in patients with Morquio A syndrome was associated with a significant improvement outcome in the ‘after’ treatment period. Keywords: Morquio Syndrome, MPS IV, Morquio A, Elosulfase Alfa, Pediatric, Iran 1. Background Morquio syndrome, mucopolysaccharidosis type 4 (MPS IV), is an autosomal recessive lysosomal storage disease in which the body cannot process certain gly- cosaminoglycans (GAGs). In MPS IV, the defect of the N- acetyl-galactosamine-6-sulfatase enzyme leads to accumu- lation of GAG chondroitin-6-sulfate (C6S) and keratan sul- fate (KS), which are synthesized primarily in the cartilage. This causes various skeletal manifestations, multisystemic impairments, and significant morbidities (1, 2). The esti- mated rate of MPS IV is approximately 1 in every 71,000 live births in the United Arab Emirates, 1 in every 500,000 live births in Japan (3), and 1 in every 200,000 live births in Aus- tralia (4). Prenatal diagnosis is possible through enzyme detection in chronic villous samples (5). Postnatal diagno- sis is performed through enzyme detection in plasma and fibroblasts and the presence of KS in urine (4). Patients with MPS IV usually appear normal at birth. Distinctive skeletal abnormalities often appear in the first years of life and include disproportionate short stature with shortness of trunk and neck, pectus carinatum, kyphoscoliosis, genu valgum, joint laxity with gradual loss of ability, wrist hyperextension, and spinal complica- tions such as odontoid hypoplasia, cervical instability and kyphoscoliosis (2, 6, 7), which may result in frequent sur- gical interventions (1, 8). The severe spinal abnormalities associated with MPS IV may contribute to cardiovascular and respiratory problems such as obstructive sleep apnea (OSA). OSA commonly occurs and is caused by an enlarged Copyright © 2021, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.