In order to quantify the B19 positive units, the quantitative DNA amplification method is used, and primers designed to detect all three genotypes are required. Many in-house PCR methods and #links# one commercial PCR method, designed before the identification of B19 genotypes, are prone to miss B19 genotypes 2 and 3 (Hokynar et?al, 2004; Baylis et?al, 2004; Koppelman et?al, 2004, 2007). Consequen