We identified the pathogenic c.271G > A missense mutation (heterozygous) in exon 2 of the TREX1 gene in one Korean family with HSP showing an autosomal dominant inheritance (Fig. 6A and Supplementary Fig. 5A); in this family, the patient and his mother were diagnosed with HSP with insidious onset of lower extremity spasticity and weakness, brain atrophy, and white matter change (Supplementary Fig. 5B and Supplementary Table 1). The gene discussed is TREX1; the disease is hereditary spastic paraplegia.