LINKAGE OF A LOCUS FOR AUTOSOMAL-DOMINANT FAMILIAL SPASTIC PARAPLEGIATO CHROMOSOME 2P MARKERS

'Pure' autosomal dominant familial spastic paraplegia (SPG) is a neuro degenerative disease which clinically manifests as spasticity of the l ower limbs. Dominantly inherited SPG is known to be clinically heterog enous and has been classified into late-onset and early-onset types, b ased on the age of onset of symptoms. We tested five autosomal dominan t SPG families for genetic linkage and established linkage to chromoge ne 2p markers(Z(theta) = 3.65) with evidence of genetic locus heteroge neity. Three late-onset SPG families and one early-onset SPG family ha d high posterior probability of linkage (P>0.94) to chromosome 2p, whi le the fifth family (a very early-onset family) was not linked to chro mosome 2 and showed high probability of linkage to chromosome 14q. The se data provide a basis for a classification of SPG according to chrom osome location rather than age of onset of symptoms.