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DOI: 10.1055/s-0030-1265524
Phenotype and long-term follow-up of juvenile Selenoprotein N1-related myopathy (SEPN1-RM)
Introduction: The SEPN1-related myopathy (SEPN1-RM) is an autosomal-recessive early onset muscle disorder characterised by distinct myomorphologies.
Objective: To characterise the phenotype in juvenile SEPN1-RM.
Methods: Retrospective multicentre study of the clinical findings, histomorphological studies and genetic data of 26 juvenile patients (8 male, 18 female) with SEPN1-RM.
Results: Muscle biopsies of 22 individuals revealed multiminicores (n=7), congenital fiber-type disproportion (n=2), myopathic changes with single cores (n=3) and unspecific myopathic features (n=10). Genetic analyses showed a variable distribution of mutations in the SEPN1 gene. Age of manifestation varied within the first two years of life with muscle hypotonia, head lag and delayed motor development. 24/26 patients were ambulant for at least 500 metres at a mean age of 14.5 years. 22 patients exhibited a rigid spine (mean age: 11.8 years) and 22 individuals had a scoliosis (mean age: 9.2 years). 11/22 patients had a scoliosis operation (mean age: 12.6 years). Spirometry was available in 19 individuals and all revealed moderate to severe respiratory impairment with a vital capacity ranging from 24–65%. 15/26 patients were intermittently nocturnally ventilated (mean age: 11.2 years). Two children had a tracheotomy, one child died at the age of three years following acute respiratory failure. Cardiac investigations were performed in 21/26 patients and revealed a mitralvalve prolapse in one and sinustachycardia prior to non-invasive ventilation in two patients. Body mass index was below 20 (kg/m2) in 20/22 patients, mean BMI 14.2 (min. 11.1, max 22.1) at a mean age of 11.7 years. 16/20 children had a birth weight >3000 gram, 4/20 children weighed between 2000–3000 gram (all patients were delivered >36. week of gestation).
Conclusion: Respiratory impairment, deformity of the spine and low body mass index are major features in juvenile SEPN1-RM. Selective symptomatic treatment is important for these patients.