Linkage of autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum to chromosome 15q13-15

To date, three loci for autosomal recessive hereditary spastic paraplegia ( ARHSP) linked to chromosomes 8p12-q13, 16qter, and 15q13-15 have been chara cterized. We have clinically characterized 13 Japanese ARHSP families and p erformed genetic linkage analyses. All 13 families were classified as havin g the "complicated" form, which manifests with mental impairment and thin c orpus callosum. Linkage to the 8p12-q13 and 16qter loci was excluded, altho ugh 10 of the 13 families showed marker data consistent with linkage to the 15q13-15 locus. The multipoint LOD score of the 10 families linked to chro mosome 15 was above 9.00 in the 3-centimorgan segment flanked by D15S994 an d D15S659, with a maximum multipoint LOD score of 9.68 at a position 1.2 ce ntimorgans telomeric from D15S994 to D15S659. We have shown that ARHSP with thin corpus callosum, a subtype of recessive spastic paraplegia, maps to c hromosome 15q13-15.