Table 1.
Participant characteristics
| Characteristic | Group | Test for group difference | ||
|---|---|---|---|---|
| XY | XYY | Statistic | p | |
| Total sample size | 60 | 64 | - | - |
| Age (years) | ||||
| Mean (s.d.) | 13.1 (5) | 13.1 (6) | t = 0 | p = 1 |
| Range | 5–24 | 5–25 | ||
| Full-scale IQ | ||||
| Mean (sd) | 117 (11) | 86 (14) | t = − 14.1 | p < 0.0001 |
| Range | 88–144 | 53–112 | ||
| SES | ||||
| Mean (sd) | 39 (16) | 53 (19) | t = 4.4 | p < 0.0001 |
| Range | 20–77 | 20–95 | ||
| Gestation (weeks) | ||||
| Mean (sd) | 39.2 (2) | 38 (2) | t = − 2.9 | p = 0.004 |
| Range | 32–42 | 31–42 | ||
| Birthweight (kg) | ||||
| Mean (sd) | 3.55 (0.5) | 3.26 (0.6) | t = − 2.8 | p = 0.006 |
| Range | 2.5–4.7 | 1.6–4.5 | ||
| Time of XYY diagnosis | ||||
| Prenatal, n (%) | - | 25 (39) | - | - |
| Postnatal, n (%) | - | 39 (61) | ||
| Vineland adaptive behavior composite score | ||||
| Mean (sd) | - | 76 (13) | - | - |
| Range | - | 42–112 | ||
| Caregiver strain (CSQ score) | ||||
| Mean (sd) | - | 7 (3) | - | - |
| Range | - | 3–14 | - | - |