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Outcome in hemoglobin SC disease: A four‐decade observational study of clinical, hematologic, and genetic factors
Author(s) -
Powars Darleen R.,
Hiti Alan,
Ramicone Emily,
Johnson Cage,
Chan Linda
Publication year - 2002
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.10140
Subject(s) - medicine , gastroenterology , incidence (geometry) , fetal hemoglobin , thalassemia , hemoglobinopathy , hemoglobin , disease , pediatrics , pregnancy , fetus , biology , physics , optics , genetics
Abstract Over the past 40 years, we observed 284 subjects with hemoglobin SC disease (Hb SC) for 2,837 person‐years. We examined the association of the course of clinical events with hematologic and genetic factors. The mean entry age was 21 years, although 15% entered before one year of age. The mean Hb concentration was 11.3 g/dL, the mean fetal hemoglobin was 2.5%, and the mean MCV was 84.4 fL. Twenty‐five subjects died at a median age of 37 years. Chronic organ‐specific complications occurred in 112 subjects (39.4%), with advanced retinopathy in 65 subjects (22.9%) and osteonecrosis (avascular necrosis) in 42 subjects (14.8%). We identified the β‐globin haplotypes in 82 subjects and the α‐gene status in 79. Twenty‐nine percent had α‐thalassemia‐2. The β CI haplotype was present in 85.4%. We found a decreased incidence of retinopathy in the β CI subjects compared to the non‐β CI subjects (33% vs. 67%; P = 0.049) with a later mean onset age (29 years vs. 21 years; log‐rank test, P = 0.026). We also found a consistent pattern of decreased morbidity in subjects who had α‐thalassemia‐2 in comparison to those who did not. We found a reduced risk of chronic organ‐specific complications (log‐rank test, P = 0.003), lower incidence of sickle crisis (48% vs. 80%, P = 0.001), later onset of gallbladder disease (age of onset: 55 years vs. 34 years; P = 0.055), and lower risk of osteonecrosis (log‐rank test, P = 0.024). Our findings suggest that Hb SC subjects who have not inherited α‐thalassemia‐2 might benefit from erythrocyte rehydration therapy. Am. J. Hematol. 70:206–215, 2002. © 2002 Wiley‐Liss, Inc.