A comparison of the physical and intellectual development of black children with and without sickle-cell trait

Sickle-cell trait, a condition present in 7% to 9% of the United States Black population, is usually considered to be a clinically benign condition. However, there is increasing evidence to indicate the contrary, that is, the clinical pathophysiology is variable, ranging from a benign condition in most cases to a relatively few cases of severe pathological involvement. Physical and intellectual growth measures were taken on 19 children with sickle-cell trait (12 boys and 7 girls) from a large study of Black same-sex twin pairs from Philadelphia, Pennsylvania, and compared to measures taken of a sample of normal Black children from 155 monozygotic and dizygotic same-sex twin pairs. Sickle-cell trait carriers were found to weigh less, have smaller upper arm circumference lesser skinfold thickness, and showed less mature skeletal age, differing significantly from normal children. Sickle-cell carriers tended to score lower on four of five intellectual measures, scoring one fifth to one third of a standard deviation lower than normal children.