A novel homozygous exon 2 deletion of TRIM32 gene in patient with sarcotubular myopathy – case report

The research group

Background

Sarcotubular myopathy (STM) is a rare autosomal recessive disease characterized predominantly by weakness of the proximal limb. Mutations in the TRIM32 gene are often associated with STM and the limb-girdle muscular dystrophy R8 (LGMDR8). Since the first case was reported in Jerusalem in 1973, STM has only been described in 28 patients across the world. The article published in BJBMS reviews in detail the pathogenic TRIM32 mutations of sarcotubular myopathy. The aim of this review is to report that a worldwide distribution of this very rare disease and elaborate that the clinical manifestation of individuals with homozygous deletions of TRIM32 may not correlate with a higher severity in phenotype.

What did the researchers do and find?

By light microscopy, muscle biopsy exhibited vacuoles in scattered myofibers. Magnetic resonance imaging (MRI) revealed a preferential fatty infiltration in the posterior compartment of the patient’s thigh, with marked sparing in the gracilis, sartorius and quadriceps muscles. There was more focal involvement in the gastrocnemius muscles. The upper limb muscles demonstrate minimal fatty infiltration and no distinct involvement pattern. Whole exome sequencing (WES) detected that the patient had one homozygous exon 2 deletion in the TRIM32 gene. The presence of this homozygous deletion was confirmed with quantitative real-time PCR.

What is the contribution of this study to our knowledge?

In conclusion, this report suggests that TRIM32 mutations should be considered in the genetic diagnosis of vacuolar myopathy. TRIM32 inactivation may not influence cognitive impairment in STM patients.

Reference

Wei X-J, Miao J, Kang Z-X, Gao Y-L, Wang Z-Y, Yu X-F. A novel homozygous exon2 deletion of TRIM32 gene in a Chinese patient with sarcotubular myopathy: A case report and literature review. Bosn J of Basic Med Sci. 2020

Editor: Edna Skopljak, MD

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