PP03.5 – 2756: Multiple symmetrical lipomatosis: An uncommon presentation of a mitochondrial disease

Abstract

Objective To evaluate the possibility of mitochondrial involvement in a patient with multiple symmetrical lipomatosis (MSL) by testing mitochondrial DNA (mtDNA) in lymphocytes, skeletal muscle and adipose tissue, and by assaying OXPHOS complex activities in skeletal muscle. Methods Several tissues (lymphocytes, skeletal muscle, adipose tissue) from one patient originating from a family affected by MSL on three generations has been assayed using biochemical and molecular tests to detect mtDNA alterations and OXPHOS deficiencies as potential cause of MSL. Results mtDNA sequencing in patient's lymphocytes revealed the presence of the classic MERRF mutation (m.8344A> G) in heteroplasmic state (40%) which was even higher in skeletal muscle (68%) and adipose tissue (94%). Spectrophotometric analysis of OXPHOS activities in skeletal muscle homogenate revealed a decreased but not deficient activity of complex IV. Analysis in isolated skeletal muscle mitochondria using BN-PAGE followed by in–gel activity staining showed overall low activities of complexes I, III and IV which are the complexes containing subunits that are encoded by mtDNA and additionally revealed presence of subcomplexes of complex V. This latter is a hallmark of a defect in intramitochondrial translation. Conclusion MSL also known as Ekbom's syndrome, Madelung's disease and Launois-Bensaude syndrome is an unusual disorder characterized by the presence of lipomas with axial symmetrical distribution. Currently the pathogenic mechanisms are not known. In our opinion, assays of the OXPHOS complexes and mtDNA analysis are indicated in a patient presenting multiple symmetrical lipomatosis, especially with positive familial history. As this clinical feature may be the first sign of a mitochondrial disease extensive clinical evaluation and follow-up of these patients is mandatory.