Natural Killer (NK) cells are innate immune cells that mediate antiviral and antitumor responses. NK cell activation and induction of effector functions are tightly regulated by the integration of activating and inhibitory receptors such as killer immunoglobulin-like receptors (KIR). KIR genes are characterized by a high degree of diversity due to presence or absence, gene copy number and allelic polymorphism. The aim of this study was to establish the distribution of KIR genes and genotypes, to infer the most common haplotypes in an admixed Colombian population and to compare these KIR gene frequencies with some Central and South American populations and worldwide. A total of 161 individuals from Medellin, Colombia were included in the study. Genomic DNA was used for KIR and HLA genotyping. We analyzed only KIR gene-content (presence or absence) based on PCR-SSO. The KIR genotype, most common haplotypes and combinations of KIR and HLA ligands frequencies were estimated according to the presence or absence of KIR and HLA genes. Dendrograms, principal component (PC) analysis and Heatmap analysis based on genetic distance were constructed to compare KIR gene frequencies among Central and South American, worldwide and Amerindian populations. The 16 KIR genes analyzed were distributed in 37 different genotypes and the 7 most frequent KIR inferred haplotypes. Importantly, we found three new genotypes not previously reported in any other ethnic group. Our genetic distance, PC and Heatmap analysis revealed marked differences in the distribution of KIR gene frequencies in the Medellin population compared to worldwide populations. These differences occurred mainly in the activating KIR isoforms, which are more frequent in our population, particularly KIR3DS1. Finally, we observed unique structural patterns of genotypes, which evidences the potential diversity and variability of this gene family in our population, and the need for exhaustive genetic studies to expand our understanding of the KIR gene complex in Colombian populations.

Throughout our lives we take different decisions, about our culture, our food, our likes, our future, and in some moments we decide to make some voyages of learning. On this road we learn a lot, even more than hoped for, in my case, as I received so many unexpected and valuable lessons that it now only remains for me to express my thanks. This master's degree is more than a new professional qualification for my curriculum vitae, it has been a life experience, since it taught me how to get lost and how to go back, to find myself. It taught me to let myself be guided and accompanied, reiterating that in this life all that we learn is useful, that all people who arrive in our lives have a lot to bring to us, and something too that one can contribute. And it was in this during this journey that I found so many beautiful and nice people that I haven't mentioned in these paragraphs. To them I express my deepest esteem and my sincere acknowledgment. Thanks to my quartet of classmates Cesar Garcia, Diana Grajales, Isis Hernández, and VictorLópez, because with them the postgraduate studies were amazing, filled with learning and laughter. I thank them for their support and friendship, the best possible example of the way such relationships can be built between professionals. A special acknowledgment to Diana Grajales because only somebody so in love with studying and chemical engineering can understand me and help me to rediscover my inspiration, thanks so much. To the teacher Adriana Villegas, thank you for giving me cardiopulmonary resuscitation in a time of agony, because when my PC was broken, she helped me with all her tools and time to allow me to continue.To my advisor Dr. Silvia Ochoa, the most intelligent person, the best teacher and person that I know, thanks for your lessons, advice, and mainly your patience and good talks about the academy and life, maybe I need another thesis to express to her all my gratitude. When I met my advisor, I said that I loved the modeling and simulation of processes and saw that with her I could learn a lot about the programing applied to chemical engineering. I wasn't wrong in my thinking, by contrast, I underestimated this, because not only had I met a great teacher with wide knowledge in mathematics, thermodynamics, control, simulation, amongst other areas of science, and other great quantity of mental capacities, but also I found an excellent person who shares her expertise, and shows more than just interest in her students but interest in the people who are her students, and she helps you to grow as such. Thank you for making sure my postgraduate studies were not just another technical stage, thank you for making me a better person and better professional, and mainly thank you for allowing me to get to know you, and for believing in me, because although I had bad days she always was my cornerstone, motivating and improving my skills and working on my weaknesses, and never allowing me to decline, reminding me of the reasons why I chose to research in modeling and simulation of p...