Background The Pediatric Spinal Muscular Atrophy Registry Program of Iran (PSMAIR) was established as part of the global TREAT-NMD network, which collects data from spinal muscular atrophy (SMA) patients under 18 years of age in Iran. The registry employs a web-based data entry system to collect detailed longitudinal demographic, geographic, clinical, genetic, and treatment outcome data of Iranian children who suffer from SMA. Results From October 2021 to September 2022, 59 SMA patients were enrolled; 52.5% were female, 47.5% were male, and the average age was 4.98 ± 4.08 years. The majority of registered patients were diagnosed with SMA Type I (47%), followed by Type II (29%) and Type III (24%). Overall, about 19% of the registered patients died; all of them were Type I patients. In the registry, 44% of patients had been hospitalized previously. Usage rates for wheelchairs or other mobility assistive devices, occurrence of scoliosis, tube feeding, and mechanical ventilation among these patients were 15%, 15%, 19%, and 20%, respectively. The data reveal a gradient of severity across SMA types, with earlier symptom onset, lower CMAP amplitude, and lower ACTIVLIM scores associated with more severe SMA (type I), and increments observed moving towards milder forms (type III). The data reveal that symptom onset age, CMAP amplitude, and ACTIVLIM scores progressively increase from SMA type I to SMA type III. The CHOP-INTEND questionnaire’s average score was notably higher in children with SMA type II compared to those with type I, while the HFMSE questionnaire scores were notably increased in type III compared to type II patients. A significant correlation between the SMN2 copy number and the SMA phenotype was observed in the population. The geographic distribution of the enrolled patients covers 15 and 18 (out of the 31) provinces of Iran for place of birth and current place of residence, respectively. For patients residing outside Tehran city (where the registry’s referral center is located), the average distance to the registry’s referral center was roughly 463 km.

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