LINKAGE OF PURE AUTOSOMAL RECESSIVE FAMILIAL SPASTIC PARAPLEGIA TO CHROMOSOME-8 MARKERS AND EVIDENCE OF GENETIC-LOCUS HETEROGENEITY

'Pure' familial spastic paraplegias (FSP) are neurodegenerative disord ers that are clinically characterized by progressive spasticity of the lower limbs and are inherited as autosomal dominant (DFSP) or autosom al recessive (RFSP) traits. The primary defect in FSP is unknown. Gene tic linkage analysis was applied to five RFSP families from Tunisia. I n four of these five families tight linkage of the RFSP locus was esta blished to the chromosome 8 markers, D8S260, D8S166, D8S285, FLAT, and D8S279. The RFSP locus in the fifth family was not linked to these ma rkers which provided evidence of genetic locus heterogeneity in RFSF. Identification of the RFSP gene on chromosome 8 will help in understan ding the genetic factors in motor neuron degeneration.