RT-PCR analysis of chromosome 21-localized transcript levels in myeloblasts obtained from newly diagnosed patients with AML or TMD. Lanes DS 1 through 10 and non-DS 1 through 20 correspond to the patients listed in Tables 1 and 2, respectively. CBS, cystathionine-β-synthase localized to 21q22.3 corresponding to a 655-bp product; SOD, superoxide dismutase localized to 21q22.1 corresponding to a 436-bp product. The transcript levels were normalized to 18S RNA transcript levels.