RPS17 copy number and expression by Q-RT-PCR. (A) Copy number at RPS17 was measured after internal normalization to an intergenic region of the β-hemoglobin locus in 3 normal control individuals, the 1314 and 20QL probands, and their parents. Normal copy number (ie, 4N) was defined as the average of 3 normal control individuals in each experiment. Both DBA probands showed reduced copy number at RPS17. (B) RPS17 expression levels were measured by internal normalization to RPL35A. Both deletion probands manifest haploinsufficiency of RPS17 mRNA, with levels consistent with approximately 50% expression. Graphs depict the average of 3 independent experiments, with each control and reference gene assayed in triplicate at each experiment. Normal expression (1.0) was taken as the average of 3 normal individuals in each experiment. Error bars depict the SEM. *P < .001 and **P < .0001 by unpaired t test compared with averaged normal controls.