Mutations in the key enzyme of sialic acid biosynthesis, UDP-N-acetylglucosamine 2-epimerase/N-acetyl-mannosamine kinase, result in distal myopathy with rimmed vacuoles (DMRV)/hereditary inclusion body myopathy (HIBM) in humans. Sialic acid is an acidic monosaccharide that modifies non-reducing terminal carbohydrate chains on glycoproteins and glycolipids, and it plays an important role in cell...

Mutations in the valosin containing protein (VCP) gene cause hereditary Inclusion body myopathy (hIBM) associated with Paget disease of bone (PDB), frontotemporal dementia (FTD), more recently termed multisystem proteinopathy (MSP). Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s. Histolog...

GNE myopathy (GNEM), also known as hereditary inclusion body myopathy (HIBM), is a late- onset, progressive myopathy caused by mutations in the GNE gene encoding the enzyme responsible for the first regulated step in the biosynthesis of sialic acid (SA). The disease is characterized by distal muscle weakness in both the lower and upper extremities, with the quadriceps muscle relatively spared u...

Academic Dissertation To be publicly discussed with permission of the Medical Faculty of the University of Helsinki, in the small lecture hall of the Haartman Institute, This thesis is based on the following original articles, which are referred to in the text by their Roman numerals. In addition, some unpublished data are presented. Secondary calpain3 deficiency in 2q-linked muscular dystrophy...

TDP-43 is a 414 amino acid protein encoded by the transactive response (TAR) DNA binding protein gene on chromosome 1p36. It was first cloned as a human protein capable of binding to the TAR DNA of HIV-1.11 It was later identified as part of a complex involved in splicing of the cystic fibrosis transmembrane conductance regulator gene.3 TDP-43 is highly conserved, ubiquitously expressed and pre...