Muscle Imaging Approaches in Marinesco-Sjögren Syndrome: A Systematic Review and Two New Clinical Reports

Background: Marinesco-Sjögren syndrome (MSS, MIM #248800) is a condition that is characterized by biallelic pathogenic variants in the SIL1 gene. Manifestations include congenital cataracts, cerebellar ataxia, progressive muscle weakness and skeletal deformities, delay in psychomotor development, hypergonadotropic hypogonadism and short stature. Muscular involvement has been extensively discussed as a clinical finding but there is little literature on muscle imaging. The aim of this paper is to systematically review muscular imaging techniques in MSS reported in the literature, and to describe the clinical and imaging features of two pediatric subjects with MSS. Methods: Having searched through three electronic databases (PubMed, Scopus and Web of Science) two articles, written in English, describing twelve patients with MSS mutations on whom muscle MRI imaging was performed, were selected. In addition, two paediatric cases (brother and sister) with Marinesco-Sjögren syndrome (MSS) and MRI muscle findings were added. Data on type of study, cohort characteristics, type of mutation, neuromuscular signs and symptoms, imaging assessment, electrophysiological findings, biopsies, CNS symptoms, ocular signs and muscle imaging data were collected and stored in a table. Results: Of the 239 articles examined, only 3 used a muscle imaging technique to describe myopathy in MSS; one used a CT while another a muscle MRI. All 14 patients showed signs of fatty replacement. The infiltration mainly affected the lower limbs, but involvement in the upper limb was described in some adult patients. Conclusions: Performing a muscle MRI in MSS can lead to the early identification of muscle involvement and may be a useful biomarker to monitor disease progression.