Sistema Vel: triagem molecular utilizando DNA obtido de pools de plasma de doadores de sangue

Abstract

Serologic methods to determine the Vel-phenotype require the use of rare human antisera and do not allow for many samples to be tested simultaneously, which limits their application as a tool to search for rare donors. This study developed a low-cost molecular screening strategy using the real-time polymerase chain reaction (PCR) with DNA extracted from plasma pools used for viral nucleic acid test (NAT) screening, to identify Vel-and Vel+ W donors. A total of 25,322 blood donors from the Brazilian southeast region were genotyped through real-time PCR targeting the 17-nucleotide (c.64_80del17) deletion in the SMIM1 gene, which determines the Vel-phenotype, by using leftover nucleic acid from plasma pools of six donors, routinely discarded after the release of viral NAT results. One hundred and eighty eight from 4,220 pools tested were reactive. The SMIM1*64_80del17 deletion was present in 210 donors, 208 (0.4%) in heterozygosity and only 2 in homozygosis (0.008%). The DNA pool genotyping strategy using real-time PCR designed to detect the deletion in the SMIM1 gene proved effective and accurate in identifying donors with the Vel-and Vel+ W phenotypes. The fact that residual nucleic acid from routine viral NAT screening was successfully employed renders this technique economically attractive and definitely superior to the serologic techniques available to search for this rare phenotype.