A rare, complex form of hereditary spastic paraplegia characterized by an onset in infancy of spastic paraplegia (presenting with the inability to walk unsupported and a scissors gait) associated with a motor and sensory polyneuropathy with loss of terminal digits and acropathy. SPG61 is due to a mutation in the ARL6IP1 gene (16p12-p11.2) encoding the ADP-ribosylation factor-like protein 6-interacting protein 1.