Forty-nine patients with familial clustering of hematological malignancies. (A) Familial history follow-up indicates that 15% of the patients have an affected first-degree, second-degree, or third-degree relative with a hematologic malignancy. (B) Number of pathogenic/likely pathogenic and VUS germline variants in patients with familial clustering. (C) Co-occurrence of somatic mutations in patients harboring germline variants and familial clustering. A full list of somatic and germline variants is included in supplemental Table 7.