TCR repertoire in trisomy 8 and monosomy 7. Thirty-three patients (light bars) with trisomy 8 (including 5 with complex cytogenetics), 11 patients with monosomy 7, and 19 age-matched healthy donors (dark bars) were studied. PBMC preparations were stained with CD28 FITC- and PE-conjugated mAbs directed against individual TCR-Vβ subfamilies and subjected to flow cytometry. Patients were compared with 19 age-matched controls. (A) Vβ subfamily distributions for a selection of patients with monosomy 7, only one of whom showed evidence of T-cell expansion. Values for each patient sample (light bars) are superimposed on mean of normal cohort (dark bars). (B) Examples of the Vβ subfamily distributions of patients with trisomy 8, all of whom showed expansion of Vβ subfamilies.