# A novel DNM2 variant associated with centronuclear myopathy: a case report

## TL;DR

A new DNM2 gene variant in the PH domain is linked to centronuclear myopathy in a 47-year-old man with progressive muscle weakness.

## Contribution

Reports a previously unreported DNM2 variant (c.1726G>A, p.Glu576Lys) associated with centronuclear myopathy.

## Key findings

- The patient presented with progressive muscle weakness starting at age 40.
- Muscle biopsy showed central nuclei and radial sarcoplasmic strands in some fibers.
- The variant is located in the PH domain of dynamin-2 and expands the known DNM2-related myopathy spectrum.

## Abstract

DNM2 encodes the dynamin-2 protein, a GTPase involved in clathrin-mediated endocytosis and other membrane trafficking pathways. The dynamin-2 protein is composed of several functional domains, including a GTPase domain, a middle domain, a pleckstrin homology (PH) domain, a GTPase effector domain (GED), and a proline-rich domain. Monoallelic variants in DNM2 are associated with Charcot–Marie–Tooth disease and a rare form of congenital centronuclear myopathy (CNM). Several DNM2 variants have been reported in patients with CNM, typically presenting with mild and slowly progressive symptoms. We report the case of a 47-year-old man with DNM2-related myopathy, who presented with progressive muscle weakness starting at the age of 40 years. Clinical exome sequencing revealed the presence of a heterozygous DNM2 variant c.1726G>A, p.(Glu576Lys). This variant, previously unreported, is located in the PH domain of the protein. Muscle biopsy findings showed several fibers with central nuclei, sometimes multiple. In addition, occasional centronucleated fibers showed a radial distribution of sarcoplasmic strands. This study expands the clinical and genetic repertoire of DNM2-related myopathy.