Fetal hemoglobin and clinical severity of homozygous sickle cell disease in early childhood.

The relationship of the clinical features of homozygous sickle cell disease in the first two years of life to the level of fetal hemoglobin at age 6 months was investigated. Mean HgbF levels were significantly lower in children manifesting early palpable splenomegaly, dactylitis, acute splenic sequestration, and in those who died. The risks of dactylitis and ASS were significantly greater in patients with lower HgbF levels. Since early splenomegaly itself may increase the risks of ASS, infection, and death, the relationship of HgbF to these features was further analyzed within the early splenomegaly group. The results suggest that a low HgbF may have a direct effect on the etiology of ASS, but any effect on infection or death is probably mediated via its relationship with the appearance of a palpable spleen. A protective effect of a high HgbF on the risk of dactylitis was demonstrated coincident with the accepted theory of its pathogenesis. Early HgbF determinations may be of value in identifying patients at high risk of serious complications during infancy.