disease:Defects in VAPB are a cause of spinal muscular atrophy autosomal dominant Finkel type (SMAF) [MIM:182980]; also called late-onset spinal muscular atrophy Finkel type or spinal muscular atrophy proximal adult autosomal dominant. Spinal muscular atrophy refers to a group of neuromuscular disorders characterized by degeneration of the anterior horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy. SMAF is characterized by proximal muscle weakness that begins in the lower limbs and then progresses to upper limbs, onset in late adulthood (after third decade) and a benign course. Most of the patients remain ambulatory 10 to 40 years after clinical onset.,disease:Defects in VAPB are the cause of amyotrophic lateral sclerosis type 8 (ALS8) [MIM:608627]. ALS8 is a familial form of amyotrophic lateral sclerosis, a neurodegenerative disorder affecting upper and lower motor neurons and resulting in fatal paralysis. Sensory abnormalities are absent. Death usually occurs within 2 to 5 years. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of cases leading to familial forms.,function:May play a role in vesicle trafficking.,online information:ALS genetic mutations db,similarity:Contains 1 MSP domain.,subcellular location:Present in the plasma membrane and in intracellular vesicles.,subunit:Homodimer, and heterodimer with VAPA. Interacts with VAMP1 and VAMP2. Interacts with HCV NS5A and NS5B.,tissue specificity:Ubiquitous. Isoform 1 predominates.,
Endoplasmic reticulum membrane ; Single-pass type IV membrane protein . Present in mitochondria-associated membranes that are endoplasmic reticulum membrane regions closely apposed to the outer mitochondrial membrane. .
Ubiquitous. Isoform 1 predominates.