Table I.

Demographic, clinical, and genotypic characteristics of 820 Black or African American SIT Trial participants.

Characteristic*	Mean (SD) or %
Age at registration (years)	8.9 (2.5)
Male (%)	52.3
Ever had asthma (%)	23.4
Steady-state white blood count (×109/l)	12.7 (5.5)
Steady-state haemoglobin (g/l)	81 (11)
Steady-state reticulocytes	12.2 (5.3)
Total bilirubin (µmol/l)	65 (46.2)
α-globin genotype (%)
αα/αα	58.3
−α/αα	36.3
−α/− α	5.4
HMOX1 promoter (GT)n genotype** (%)
L/L	73.1
S/L	23.2
S/S	3.7

^*Steady-state levels defined at a single routine clinical well visit.

^**(GT)_n allele classes defined by number of repeats: S ≤ 25 and L > 25.