Recessive mutations in SPG7 (spastic paraplegia 7) and dominant mutations in PEO1 (progressive external ophthalmoplegia 1) were the most common pathogenic nDNA mutations identified in clinically affected individuals (SPG7: minimum prevalence = 0.8 × 10−5, 95% CI = 0.5–1.3 × 10−5; PEO1: minimum prevalence = 0.7 × 10−5, 95% CI = 0.4‐1.2 × 10−5). This evidence concerns the gene TWNK and Spastic paraplegia.