Patients with neutral lipid storage disease with myopathy (NLSDM) in Southwestern China

Abstract

Objectives: Neutral lipid storage disease with myopathy (NLSDM) is a rare metabolic myopathy occurring owing to mutations in the patatin like phospholipase domain containing 2 (PNPLA2) gene. Till date, less than 50 patients with PNPLA2 mutations have been reported. In this study, we describe the clinical, pathological, and genetic findings, and muscle magnetic resonance imaging (MRI) changes in four Chinese patients with NLSDM.

Patients and methods: Peripheral blood smears were stained using Wright's stain. Muscle biopsies, muscle MRI, and sequence analysis of PNPLA2 gene were performed.

Results: All patients exhibited slowly progressive myopathy during adulthood. Cardiomyopathy, sensorineural hearing loss, hepatic adipose infiltration, and hypertriglyceridemia were observed in some patients. Jordan's anomaly was detected in the blood smears of all patients. Muscle biopsies revealed the presence of massive lipid droplets and rimmed vacuoles in two patients. MR images of the lower lumbar, pelvis, and lower extremities showed the involvement of posterior compartment muscles. The anterior compartment muscles were found to be less affected. Gene analysis for PNPLA2 revealed an identical homozygous mutation c.757 + 1G > T in all patients.

Conclusion: Patients with NLSDM display clinical heterogeneities despite sharing the same mutation (c.757 + 1G > T) of the PNPLA2 gene, may suggest a founder effect in the region.

Keywords: Adipose triglyceride lipase (ATGL); Jordan’s anomaly; Muscle pathology; Neutral lipid storage disease with myopathy (NLSDM); Patatin-like phospholipase domain containing 2 (PNPLA2); Rimmed vacuoles.