Mutant MYH9 mRNA is expressed in peripheral blood cells, but to a lesser extent in platelets. (A) Genomic map of MYH9 exon 39 and 40 region and locations of primers (arrows) used for quantitative fluorescent PCR amplification. PCR was performed on cDNA samples from neutrophils, platelets, monocytes, and lymphocytes using primers 395 and 6-FAM–labeled 4035. Genomic DNA was also amplified by fluorescent PCR using primers 405 and 6-FAM–labeled 4035 for comparison. PCR products were examined using an ABI 310 Genetic Analyzer and data were analyzed. Boxes (numbered) and lines represent exons and introns, respectively, and are not drawn to scale. (B) Representative electropherograms of fluorescent PCR products from patient 2 with MYH9 5818delG. Signal ratios of mutant allele (161-bp peak) to wild-type allele (162-bp peak) are shown at right of each trace. Mean signal ratio of 4 patients is shown at far right. Ratio is approximately 0.9 in neutrophils, monocytes, and lymphocytes, but moderately decreased in platelets.