Figure 1.

Diagram illustrating how phenotypic subgroups were identified. The subgroups above the black horizontal lines were used for quantitative analysis while the ones below were used for case-control analysis. The extent of co-morbidity (hence the non-mutually exclusive definition of cases), can be seen in Figure 2. ADHD, attention-deficit/hyperactivity disorder; CCC_SUM7, sum of first seven scales from the Children's Communication Checklist; PERF_IQ, performance IQ; RD, reading disability; SLI, specific language impairment.