Distribution of S values in patients with BM failure. (A) Patients younger than 70 years. (B) Patients older than 70 years. (+) indicates patients with increased PNH-type cells; (–), patients without increased PNH-type cells. Not included in these figures are 2 PNH^– patients with clonal hematopoiesis (one is a 59-year-old AA patient and another is a 76-year-old RA patient), because 1 of 2 alleles completely disappeared after digestion of their granulocyte DNA.