This survey of 1100 Negro children in various age categories was undertaken to determine the effect of age upon the appearance of the sickling phenomenon from infancy throughout childhood. The general incidence of sickling in 1100 Negro children including sickle cell anemia and sickle cell trait was 7.4%. The data on the incidence of the asymptomatic sickling trait and of sickle cell anemia are summarized by age and sex in Tables I and II.We encountered 22 cases of sickle anemia, seven of which were previously undiagnosed and unknown. Sixteen cases of sickle cell anemia in males and six in females were encountered in the total test group, comprising 651 males and 449 females.This investigation disclosed 60 subjects bearing the asymptomatic sickling trait. There were 40 and 20 instances of asymptomatic sickling observed in 635 males and 443 females, respectively. When the sexes were divided into two age categories (1 month through 4 years and 5 years through 16 years), there was an actual decrease in the incidence of sickling in the girls and an increase in the sickling phenomenon in the boys. We have no explanation for this finding. The overall incidence of the sickling trait for both sexes in all age groups represents no significant deviation from a 1:1 ratio.The data available from this study failed to disclose a definite progressive increase in the incidence of sickling in the age groups studied. Quantitatively the general transition from the low incidence of sickling in the newborn (3.4%) to the higher occurrence in older children (7.5%) apparently takes place during the first year of life. Additional studies of both a qualitative and quantitative nature and involving a detailed age breakdown during the first year of life would probably elucidate this period of transition.
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