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Hemoglobin S and C traits: contributing causes for decreased mean hematocrit in African-American children
S R Rana1, S Sekhsaria, O L Castro
1Dept of Pediatrics and Child Health, Howard University Hospital, Washington, DC 20060.
Insights
African-American children often have lower hematocrit and hemoglobin levels. Hemoglobin C (HbAC) and hemoglobin S (HbAS) traits are linked to reduced hematocrit, potentially explaining some racial differences.
Area of Science:
- Hematology
- Pediatrics
- Genetics
Background:
- Nutritional surveys reveal lower mean hematocrit and hemoglobin in African-American children compared to white children.
- While alpha and beta thalassemias contribute, they don't fully explain the observed hematologic differences.
- High prevalence of hemoglobin S (HbAS) and hemoglobin C (HbAC) traits exists in African-American populations.
Purpose of the Study:
- To investigate the association between HbAS and HbAC traits and mean hematocrit levels in children.
- To determine if these hemoglobin variants contribute to racial disparities in hematologic values.
Main Methods:
- Comparative analysis of mean hematocrit values across different hemoglobin genotype groups (HbAA, HbAS, HbAC).
- Statistical examination of data stratified by sex and age groups.
- Utilized data from a large cohort of children (n=15637 for HbAA, n=1197 for HbAS, n=440 for HbAC).
Main Results:
- Children with HbAC and HbAS traits exhibited significantly lower mean hematocrit by 1.5 and 1 point, respectively, compared to children with HbAA.
- These statistically significant differences were observed across most age and sex subgroups, with exceptions in specific male adolescent groups.
- The presence of Hb S and C traits is directly associated with reduced hematocrit levels.
Conclusions:
- Hemoglobin S and C traits are associated with lower mean hematocrit in children.
- The high prevalence of these traits in African-American children likely contributes significantly to observed racial differences in mean hematocrit.
- Further research may elucidate the precise mechanisms underlying this association.
Abstract:
Several nutritional surveys have shown that African-American children have lower mean hematocrit and hemoglobin values than white children. While the high prevalence of both alpha and beta thalassemias in African-American children can partly account for the lower hematologic values, the remaining differences cannot be explained. African-American individuals have a high prevalence of traits for hemoglobin S (HbAS) and hemoglobin C (HbAC). The mean hematocrit of children with normal hemoglobin AA (HbAA) (n = 15637) was compared with that of children with traits for HbAS (n = 1197) and HbAC (n = 440). For both sexes, the mean hematocrit of subjects with HbAC and HbAS was 1.5 and 1 point lower, respectively, than that of subjects with HbAA. These differences were highly significant statistically. When the data were examined with regard to age and sex, statistically significant differences were present for all groups analyzed except the 11- through 14-year-old male group for HbAC and the 15- through 19-year-old male group for HbAS. Thus, the presence of Hb S and C traits is associated with a lower hematocrit. This reduced hematocrit may significantly contribute to the racial differences in mean hematocrit due to the high prevalence of these traits in African-American children.