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. The disease is Monarch Disease Ontology identifier MONDO_0014304 (hereditary spastic paraplegia 61). Also known as: ARL6IP1 autosomal recessive complex spastic paraplegia, SPG61, autosomal recessive complex spastic paraplegia caused by mutation in ARL6IP1, autosomal recessive spastic paraplegia 61, autosomal recessive spastic paraplegia type 61, hereditary spastic paraplegia type 61.