Homozygous CTSA mutation is thought to cause CARASAL by interfering with the function of cathepsin A, which protects against a systemic lysosomal storage disorder by stabilising the lysosomal enzymes β‐galactosidase and neuraminidase [124]. The gene discussed is CTSA; the disease is cathepsin a-related arteriopathy-strokes-leukoencephalopathy.