Pedigree of the family showing a statistically significant linkage between HS and a β-spectrin frameshift mutation (β-spectrin Bergen or 2441insA): (•), HS patients; (○), healthy members; hematologic data as well as sequence of the β-spectrin gene were available on 15 of 23 affected patients and 32 healthy individuals at genetic risk within the family: β, normal β-spectrin allele: β⁰, β-spectrin Bergen. Only 2 of the 23 patients have not been splenectomized (these are III-7 and IV-16). The latter is awaiting splenectomy.