Table 3.
Percent affected and percent proband-wise concordance (Con) by phenotype, zygosity, age, and affectedness (Aff) criteria.
| Outcome | Aff criterion | Age 4 |
Age 6 |
||||||
|---|---|---|---|---|---|---|---|---|---|
| MZ twins |
DZ twins |
MZ twins |
DZ twins |
||||||
| Aff | Con | Aff | Con | Aff | Con | Aff | Con | ||
| PPVT-III Vocabulary | −1.00 SD | 25.5 | 60.4 | 18.0 | 35.6 | 10.7 | 51.2 | 5.9 | 16.3 |
| −1.25 SD | 14.3 | 41.5 | 11.4 | 34.8 | 6.5 | 46.2 | 3.8 | 25.8 | |
| −1.50 SD | 8.3 | 26.7 | 6.1 | 28.6 | 3.7 | 53.3 | 1.9 | 26.7 | |
| TOLD-P:3 Spoken Language | −1.00 SD | 41.9 | 71.1 | 34.3 | 57.5 | 29.0 | 68.4 | 26.8 | 47.4 |
| −1.25 SD | 26.9 | 56.3 | 20.3 | 44.0 | 21.8 | 72.7 | 17.7 | 38.7 | |
| −1.50 SD | 9.9 | 45.7 | 8.2 | 25.0 | 14.6 | 64.4 | 10.7 | 31.1 | |
| TOLD-P:3 Semantics | −1.00 SD | 37.1 | 59.7 | 30.5 | 47.7 | 23.3 | 53.2 | 23.2 | 38.6 |
| −1.25 SD | 18.7 | 35.8 | 16.1 | 26.0 | 18.3 | 56.8 | 14.8 | 28.8 | |
| −1.50 SD | 10.1 | 28.6 | 10.1 | 22.8 | 14.1 | 56.1 | 11.3 | 25.0 | |
| TOLD-P:3 Syntax | −1.00 SD | 39.7 | 74.6 | 31.0 | 50.4 | 29.2 | 69.5 | 24.0 | 46.1 |
| −1.25 SD | 21.9 | 51.3 | 16.4 | 36.9 | 22.3 | 66.7 | 15.8 | 32.8 | |
| −1.50 SD | 15.7 | 42.9 | 10.2 | 30.0 | 18.8 | 71.1 | 12.7 | 31.8 | |
| GFTA-2 Speech | −1.00 SD | 7.4 | 56.0 | 4.3 | 37.5 | 6.5 | 53.8 | 4.2 | 5.6 |
| −1.25 SD | 4.5 | 66.7 | 2.9 | 43.5 | 4.3 | 58.8 | 1.8 | 13.3 | |
| −1.50 SD | 3.7 | 61.5 | 2.2 | 47.1 | 3.3 | 61.5 | 1.4 | 16.7 | |
| MLU | −1.00 SD | 24.8 | 55.2 | 20.6 | 29.8 | 16.9 | 47.8 | 15.6 | 25.8 |
| −1.25 SD | 17.9 | 50.8 | 15.0 | 29.3 | 12.8 | 27.5 | 10.3 | 16.1 | |
| −1.50 SD | 12.4 | 60.5 | 10.3 | 20.5 | 7.6 | 40.0 | 5.9 | 4.1 | |
| TEGI Composite | −1.00 SD | 46.3 | 78.0 | 37.7 | 61.4 | 31.3 | 69.8 | 21.7 | 41.1 |
| −1.25 SD | 40.7 | 74.3 | 32.2 | 58.3 | 26.9 | 75.9 | 19.4 | 38.8 | |
| −1.50 SD | 34.6 | 73.9 | 27.1 | 55.1 | 22.4 | 75.6 | 15.7 | 37.3 | |
| TEGI Screener | −1.00 SD | 41.8 | 78.7 | 32.7 | 57.6 | 23.4 | 55.3 | 16.4 | 40.0 |
| −1.25 SD | 35.1 | 76.8 | 28.3 | 55.8 | 19.9 | 60.0 | 13.7 | 37.6 | |
| −1.50 SD | 30.4 | 77.8 | 24.5 | 54.5 | 16.9 | 61.8 | 11.6 | 36.4 | |
| CMMS Nonverbal IQ | −1.00 SD | 12.8 | 25.0 | 12.6 | 25.5 | 5.7 | 52.2 | 3.9 | 6.1 |
| −1.25 SD | 6.8 | 8.0 | 5.8 | 25.0 | 2.0 | 1.9 | |||
| −1.50 SD | 2.9 | 20.0 | 1.8 | 13.3 | 1.2 | 0.9 | |||
Note. Proband-wise concordance for −1.25 and −1.50 SD affectedness on CMMS Nonverbal IQ at the age of 6 years was incalculable due to the small number of affected individuals (i.e., there were no instances of both members of a twin pair affected). MZ = monozygotic; DZ = dizygotic; PPVT-III = Peabody Picture Vocabulary Test–III; TOLD-P:3 = Test of Language Development–Primary: Third Edition; GFTA-2 = Goldman-Fristoe Test of Articulation–Second Edition; MLU = mean length of utterance as calculated by SALT software; TEGI = Rice–Wexler Test of Early Grammatical Impairment.