Pedigree of the proband. The R216W GATA1 mutation was found in the proband (IV-2; ←), his mother (III-2), and his maternal grandmother (II-11). Marked anemia and 60% Hb F were found in the proband; a moderate anemia and 4.8% Hb F were found in the grandmother. Both the proband and his grandmother were thrombocytopenic. The grandmother was 1 of 11 siblings, including 5 brothers, and none were known to be anemic. Siblings II-8, II-9, and II-12 collectively had 7 sons (not shown). None were known to be anemic, and none had signs or symptoms of CEP. These findings suggest that the R216W mutation is a new mutation arising in the maternal grandmother. Green box indicates R216W GATA1 mutation; red box, porphyric phenotype; blue box, anemia, thrombocytopenia and high Hb F levels.