Preserved Forearm and Hand Muscles and Diaphragm with Mild Cardiac and Respiratory Involvement in a Patient with GNE Myopathy Harboring Homozygous Variants in GNE (c.1807G>C, p.V603L) over Four Decades after the Onset

We encountered a 67-year-old Japanese man with GNE myopathy and homozygous variants (c.1807G>C, p.V603L) of the GNE gene. The patient developed weakness in the left foot at 24 years old and could only move his wrist joints and hands 43 years after the onset. This genotype is the most common variant and causes severe muscle involvement; however, the distal upper extremities are preserved until the end-stage of the disease. Although severe heart failure is rare in GNE myopathy, mild cardiac dysfunction (ejection fraction 46.1%) was observed. Furthermore, respiratory dysfunction was noted with a preserved diaphragm.