There were 112 participants in this study, 54 girls with TS and 58 without. All participants with TS had classic monosomy (they were lacking one chromosome from a pair), rather than a partial chromosomal loss.
The participant age range was 6 to 17 years old. Participants were matched by age.
Due to participants leaving the study, the study’s final year contained relatively few participants (18 total, 6 with TS). The girls had to travel to Stanford University once a year for four years, so many families found this inconvenient. Many other factors also led to participants withdrawing.