SERPING1 (MIM 606860), a regulator of the complement cascade, is also involved in HIV-1 infection (MIM 609423) as its expression is dysregulated in immature dendritic cells by Tat [14]; moreover, the protein product of SERPING1 is cleaved by HCV and HIV-1 proteases [15]–[16]. This evidence concerns the gene MTSS1 and HIV-1 infection.