SPG11 compound mutations in spastic paraparesis with thin corpus callosum.

BACKGROUND

Autosomal recessive hereditary spastic paraparesis with thin corpus callosum (ARHSP-TCC) is being increasingly recognized as a variety of spastic paraplegia with mental retardation. SPG11 gene mutations have been reported to be associated with ARHSP-TCC.

METHODS

As an independent group, we investigated SPG11 gene involvement in four individuals not previously described with either recessive or sporadic HSP-TCC presentation.

RESULTS

Chromosome 15q13-15 segregating autosomal disease haplotypes were different across the kindreds and sequencing of SPG11 identified four novel frameshift/nonsense segregating mutations and the R2034X mutation, which were in heterozygous compound status. The affected examined had decreased thalamic and bilateral paracentral frontal lobe metabolism on (18)F-flurodeoxyglucose PET.

CONCLUSIONS

Loss-of-function SPG11 mutations are the major cause of autosomal recessive hereditary spastic paraparesis with thin corpus callosum in Southern Europe, even in apparently sporadic cases. Decreased thalamic metabolism was consistently a phenotypical SPG11 mutation hallmark.