Top: Pedigree of the Eastern European family found to harbor a germline SH2B3 frameshift mutation (D231fs). Bottom: Functional domains of the SH2B3 adaptor protein: PHE-ZIP (Phenylalanine zipper); Plekstrin homology domain (Ph); SH2 (Src Homology 2 regulatory domain). The location of the germline D231fs mutation is noted. Figure is modified from Figure 1 in the article by Perez-Garcia et al that begins on page 2425.