Table 1.
Descriptive statistics
| Siblings (unaffected + affected) | Probands | t (p) | Cohen’s d a | ICC (p)b | ||||
| n | Mean (SD) | n | Mean (SD) | |||||
| SRS-2 score | ||||||||
| Parent | 113 | 53.1 (15.1) | 107 | 75.7 (12.3) | 12.1 (<0.001) | 1.64 | 0.15 (0.027) | |
| Teacher | 107 | 55.1 (15.0) | 107 | 68.3 (10.8) | 7.4 (<0.001) | 1.01 | 0.32 (0.002) | |
| CBCL/TRF ADHP score | ||||||||
| Parent | 114 | 55.9 (8.0) | 114 | 62.0 (9.4) | 5.3 (<0.001) | 0.70 | 0.20 (0.071) | |
| Teacher | 106 | 55.4 (7.6) | 113 | 60.2 (7.7) | 4.7 (<0.001) | 0.63 | 0.13 (0.196) | |
| DCDQ score | ||||||||
| Parent | 39 | 60.2 (15.9) | 44 | 44.2 (14.0) | −4.9 (<0.001) | 1.07 | 0.01 (0.486) | |
| n (%) | n (%) | χ 2 (p) | Φ a | |||||
| Clinical diagnosis | 137.8 (<0.001) | 0.78 | ||||||
| Autism | 14 (12.3) | 34 (29.8) | ||||||
| ASD | 15 (13.1) | 80 (70.2) | ||||||
| No ASD | 85 (74.6) | 0 (0.0) | ||||||
| Expressive language | 2.6 (0.104) | 0.11 | ||||||
| Nonverbal | 3 (2.6) | 8 (7.0) | ||||||
| Verbal | 107 (93.9) | 97 (85.1) | ||||||
| Missing | 4 (3.5) | 9 (7.9) | ||||||
| ADOS-2 classification | ||||||||
| Autism | – | 70 (61.4) | ||||||
| ASD | – | 17 (14.9) | ||||||
| Non-spectrum | – | 13 (11.4) | ||||||
| Missing | – | 14 (12.3) | ||||||
For SRS-2, CBCL, and TRF, a higher score indicates more severe impairment. For DCDQ, a higher score represents better functioning. For the SRS-2, a T score of 30 is the minimum obtainable. A total T score of 76 or higher is consistent with severe clinical-level symptomatology, a T score of 60 through 75 subclinical, and a T score of 59 or less as normal. For the CBCL and TRF, a T score of 50 is the minimum obtainable. A T score between 65 and 70 is considered borderline clinical and a score above 70 as clinical
SRS-2 Social Responsiveness Scale-2 (T score), CBCL/TRF ADHP DSM-oriented Attention-Deficit/Hyperactivity Problems Scale (T score), from Child Behavior Checklist and Teacher Report Form, DCDQ Developmental Disorder Coordination Questionnaire (adjusted total score), ASD autism spectrum disorder
aEffect sizes reported as Cohen’s d for t tests and phi (φ) for chi-square tests, with 0.1 considered a small effect, 0.3 a medium effect, and 0.5 or higher a large effect
bIntraclass correlation coefficients (ICC; two-way mixed, absolute agreement, average measure) are provided, calculated between siblings and probands in each pair, depicting variation within families