SPG11 and hereditary spastic paraplegia: Thinning of the corpus callosum (TCC) is a key manifestation and often only imaging feature in early SPG11-related familial or sporadic HSP, and almostly can be found in each patient, predominantly thinning in the genu and body, relatively sparing in the splenium of corpus callosum, which is also consistent with four sporadic patients reported in our study.