Sequence alterations within CYP7B1 implicate defective cholesterol homeostasis in motor-neuron degeneration.

The hereditary spastic paraplegias (HSPs) are a genetically and clinically heterogeneous group of upper-motor-neuron degenerative diseases characterized by selective axonal loss in the corticospinal tracts and dorsal columns. Although numerous mechanisms involving defective subcellular transportation, mitochondrial malfunction, and increased oxidative stress have been proposed, the pathogenic basis underlying the neuronal loss is unknown. We have performed linkage analysis to refine the extent of the SPG5 disease locus and conducted sequence analysis of the genes located within this region.

A clinical, genetic and biochemical study of SPG7 mutations in hereditary spastic paraplegia.

Mutations in the SPG7 gene, encoding the mitochondrial protein paraplegin, were the first to be identified in autosomal recessive hereditary spastic paraplegia (ARHSP). Four different SPG7 mutations have been described so far in association with both pure and complicated HSP phenotypes. Muscle biopsies from the most severely affected patients have shown histological evidence of an oxidative phosphorylation defect.