REEP1 and hereditary spastic paraplegia: We have previously reported that homozygous REEP1 knockout (KO) mice reproduce HSP with a length‐dependent degeneration of corticospinal tract fibers, thus establishing REEP1 loss‐of‐function and haploinsufficiency as causative for SPG31.[23] We have now modeled the dHMN‐associated REEP1 splice‐site variant c.304‐2A>C, which causes the in‐frame deletion of exon 5 of REEP1 in a knockin (KI) mouse model.