A new phenotype linked to SPG27 and refinement of the critical region on chromosome

Hereditary spastic paraplegias are genetically and clinically heterogeneous. Twenty-six loci have been identified to date. SPG27 was recently mapped to chromosome 10 in a single family with autosomal recessive hereditary spastic paraplegia (AR-HSP) and a pure phenotype. We describe a Tunisian family with a complicated form of AR-HSP also linked to SPG27. The parents are first cousins and 3 out of their 4 children manifest early onset progressive spastic paraparesis associated with sensorimotor polyneuropathy. In addition, the eldest girl had facial dysmorphism and short stature (-3SD). Two of the three patients were mentally retarded, and one of these also had cerebellar signs. Their ages at onset were 2, 5 and 7 years. A genome-wide scan suggested linkage to SPG27 on the long arm of chromosome 10 with a multipoint lod score of 2.54. In addition, a recombination detected in this family by haplotype reconstruction reduced the SPG27 locus from 25 to 19.6 cM. This is the first clinical description of a complicated form of spastic paraplegia, characterized by great phenotypic variability among the sibs, associated with the SPG27 locus.