Table 1.

Patient population

Feature	Controls	ERA
N	12	12
Age at diagnosis (years; median, IQR)	N/A	13.8 (12.2 – 15.2)
Age at collection (years; median, IQR)	14.1 (11.4 – 15.2)	13.9 (12.2 – 15.2)
Collection site
CoA	9, 75%	9, 75%
CHOP	2, 17%	2, 17%
HUMC	1, 8.3%	1, 8.3%
Males (n, %)	7, 58%	7, 58%
Race (n, %)
Caucasian	9, 75%	9, 75%
African-American	3, 25%	3, 25%
HLA-B27+ (n, %)	N/A	4/12, 33%

Abbreviations: CHOP = Children’s Hospital of Philadelphia; CoA = Children’s of Alabama; HUMC = Hackensack University Medical Center.