Descriptive characteristics of study subjects
| XXY (Klinefelter syndrome) (n=27) | Controls (n=87) | P value† | |
| Age (years) | 14.7±1.8 | 16.9±0.9 | <0.01* |
| Race/ethnicity, n (%) | 0.02 | ||
| Non-Hispanic white | 21 (78) | 52 (60) | |
| Hispanic | 3 (11) | 31 (36) | |
| Black | 3 (11) | 4 (5) | |
| Height z-score | 1.3±1.1 | 0.2±0.9 | <0.01* |
| Weight z-score | 0.8±1.3 | 0.5±1.1 | 0.19 |
| BMI z-score | 0.19±1.55 | 0.37±1.18 | 0.51 |
| Pubertal stage, n (%) | 0.17 | ||
| Tanner 2 | 2 (7.4) | 1 (1.1) | |
| Tanner 3 | 0 | 1 (1.1) | |
| Tanner 4 | 15 (55.6) | 32 (36.8) | |
| Tanner 5 | 10 (37.0) | 53 (60.9) | |
| Average daily METs | 68±20 | 71±16 | 0.44 |
| Muscle area (cm3) | 3175 (2949, 3870) | 4201 (3571, 5068) | <0.01* |
| Force (kg) | 30.3 (24.7, 34.9) | 37.9 (24.3, 32.4) | 0.51 |
| Triglyceride:HDL ratio | 2.1 (1.6, 2.6) | 1.6 (1.2, 2.3) | 0.03* |
| Treatment with exogenous testosterone, n (%) | 13 (48.1) | – |
Data presented as mean±SD, median (25%, 75%), or n (%).
*Statistically significant difference at an alpha of 0.05.
†Comparison between XXY and controls by Welch’s t-test, Wilcoxon rank-sum test, or χ2 test.
BMI, body mass index; HDL, high-density lipoprotein; METs, metabolic equivalents.