Other HSP subtypes associated with PN may include SPG2, SPG3A, SPG5, SPG6, SPG7, SPG10, SPG25, SPG27, SPG30, SPG31, SPG55, SPG56, SPOAN syndrome, and mutations in the mitochondrial ATP6 gene. The gene discussed is CYP2U1; the disease is poikiloderma with neutropenia.