PHB1 and hereditary spastic paraplegia: The ERLIN2 gene is mutated in families with complex recessive forms of HSP (SPG18), while ERLIN1 has been implicated in autosomal recessive cases of pure HSP (SPG62) (Novarino et al., 2014) ERLIN1 and ERLIN2 are highly homologous proteins, belonging to the SPFH (stomatin/prohibitin/flotilin/HflK/c) family, which is defined by a module of ∼180–200 amino acids that has been found in some members of the family to bind cholesterol (Browman et al., 2007).