In this issue of the Journal of Heart and Lung Transplantation, Marrón-Liñares et al report the results of an interesting study in which they evaluated 51 genes associated with the complement pathway in a small number of heart recipients to explore their relationship with antibody-mediated rejection (AMR). Next-generation sequencing was used in 46 heart transplant recipients (23 with AMR and 23 without AMR). The authors identified a significant association of 2 single-nucleotide polymorphisms with the absence or presence of AMR, respectively, p.Gly54Asp-MBL2 in the mannose-binding lectin (MBL) 2 gene and p.Asn428(p=)-CFP in the alternative complement factor properdin (CFP) gene. This article is a new contribution to the heart transplant literature. It suggests that complement single-nucleotide polymorphisms may influence circulating levels of selected proteins of both the lectin pathway and alternative complement pathways, thus potentially determining which patients will develop AMR.