Late diagnosis of spinal muscular atrophy, primary symptoms of the disease according to the patient registry of the SMA Families Foundation

Introduction. Spinal muscular atrophy 5q is a common childhood disease in the practice of a pediatrician and pediatric neurologist. Despite the introduction of neonatal screening in the Russian Federation since 2023, there is a cohort of patients who were not included in neonatal screening and the relevance of knowledge of the clinical symptoms of SMA remains.

Aim. To study the reasons for delayed diagnosis of spinal muscular atrophy in the Russian Federation.

Materials and methods. We analyzed the data of the registry of 1452 patients with SMA: the time of delay in diagnosis from the onset of the first clinical symptoms, identified the first clinical symptoms and analyzed erroneous primary diagnoses that increased the time of correct diagnosis. Patients were divided into two groups: group 1 of patients (1170) born before 2019, the second group of patients (274) born from 2019 to 2023. An analysis of the medical records of 330 patients with SMA observed at the Veltischev Scientific Research Institute was conducted in order to analyze the clinical symptoms of SMA that were underestimated by primary care physicians and led to a delay in correct diagnosis.

Results. In the 1st group of patients, 146 patients with SMA type 1, 531 SMA type 2, 493 – SMA type 3, 8 – SMA type 4 were registered. The delay in diagnosis was 4 months, 2 years 4 months, 5 years 2 months, 11 years, respectively. In the 2nd group of patients, 176 patients with SMA type 1, 81 – SMA type 2, 17 – SMA type 3 were registered. The delay in diagnosis was SMA1 – 2 months, SMA2 – 6 months, SMA3 – 6 months. Since 2019, there has been a significant decrease in the delay in diagnosis, especially for SMA types 2 and 3 up to 6 months. The primary and most significant clinical symptoms for patients with different types of SMA are determined.

Conclusions. Underestimating of clinical symptoms of spinal muscular atrophy leads to late molecular genetic diagnosis of the disease. The identified initial clinical signs of spinal muscular atrophy of different types will allow primary care physicians to suspect the disease in time and refer patients for confirmatory molecular genetic diagnostics.

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