OBJECTIVETo describe the clinical features of a big family with incompletely penetrated autosomal dominant hereditary spastic paraplegia (SPG) and perform the exclusion analysis of genetic loci.

METHODSThe clinical information of this SPG family was analyzed retrospectively. Exclusion analysis of the known autosomal dominant SPG loci was performed by using multiplex fluorescence PCR, capillary electrophoresis and Linkage package.

RESULTSThere were eleven affected members available in this SPG family and the age at onset ranged from 2 to 10 years. The first symptoms were a bilateral, symmetrical, progressive lower limb weakness and spasticity. Patients presented with spasticity and hyperreflexia, positive Babinski sign and scissors gait, and the upper limbs were involved more severely than the lower limbs. No urinary inconsistence, sensory impairment, nystagmus and dementia were found. Genetic analysis showed that this family was consistent with autosomal dominant inheritance. The linkage analysis and mutation analysis revealed this family was not linked to the known autosomal dominant loci.

CONCLUSIONThis SPG family had typical "pure" clinical symptoms. The age at onset was early and the signs in the upper limbs were more obvious than those in the lower limbs. The result of linkage analysis shows that this family represents a new SPG subtype.