The three affected members from Fam-06 were found to carry a known and homozygous pathogenic mutation (p.Met245Valfs*2) in the SPG11 gene, which is the most commonly mutated gene in complex autosomal recessive hereditary spastic paraplegia (AR-HSP), which presents with spastic paraplegia along with other clinical manifestations including ID. This evidence concerns the gene SPG11 and hereditary spastic paraplegia.