“Pure” hereditary spastic paraplegias

Spasticity is such a common and nonspecific neurologic finding that its inclusion in the description of many genetic disorders of the nervous system is not surprising. Often, arbitrary decisions have been made in the past as to which syndrome names would contain the term “spastic.” A group of pure, or uncomplicated, hereditary spastic paraplegias (HSP) were said to share the clinical hallmarks of almost exclusive progressive spasticity and weakness of the lower limbs, with occasional involvement of the dorsal columns or bladder symptoms. HSP are categorized by inheritance: autosomal dominant, autosomal recessive, or X-linked1,2 (table). This issue of Neurology characterizes two new loci. Hedera et al.3 present clinical features of a large chromosome 8q23-24–linked autosomal dominant HSP kindred, and Murillo et al.4 report linkage to a third locus—15q13-q15—for autosomal recessive HSP. The molecular characterization of HSP over the last 6 years has already shed light on the cause of two X-linked and one autosomal recessive HSP (table); the gene products associated with the remaining loci are likely to be identified soon. However, it is already possible to begin to characterize the phenotype of each disorder. View this table: Table 1. Classification of hereditary spastic paraplegias The chromosome 8q–linked5 autosomal dominant HSP kindred described in Hedera et al. includes 15 affected subjects (8 men and 7 women) whose symptoms include lower extremity spasticity and weakness, hyperreflexia, ankle …