Evaluation of parasite and host genetics in two generations of a family with Chagas disease

Narrowing the Relationship between Human CCR5 Gene Polymorphisms and Chagas Disease: Systematic Review and Meta-Analysis

Our aim was to carry out a qualitative and quantitative synthesis of the influence of CCR5 genetic variants on Chagas disease (CD) through a systematic review. A total of 1197 articles were analyzed, and eleven were included in the review. A meta-analysis was conducted along with principal component analyses (PCAs). The polymorphisms found were analyzed using the SNP2TFBS tool to identify possible variants that influence the interaction with gene binding sites. Eleven studied variants were identified: rs2856758, rs2734648, rs1799987, rs1799988, rs41469351, rs1800023, rs1800024, Δ32/rs333, rs3176763, rs3087253 and rs11575815. The studies analyzed were published between 2001 and 2019, conducted in Argentina, Brazil, Spain, Colombia and Venezuela, and included Argentine, Brazilian, Colombian, Peruvian and Venezuelan patients. Eight polymorphisms were subjected to the meta-analysis, of which six were associated with the development of the cardiac form of CD: rs1799987-G/G and G/A in the dominance model and G/G in the recessiveness model; rs2856758-A/G in the codominance model; rs2734648-T/T and T/G in the dominance model; rs1799988-T/T in both the codominance and recessiveness models; rs1800023-G allele and the G/G genotype in the codominance and recessiveness models, and the G/G and G/A genotypes in the dominance model; and rs1800024-T allele. The PCA analyses were able to indicate the relationships between the alleles and the genotypes of the polymorphisms. The SNP2TFBS tool identified rs1800023 as an influencer of the Spi1 transcription factor (p < 0.05). A correlation was established between the alleles associated with the cardiac form of CD in this review, members of the C haplotype of the gene (HHC-TGTG), and the cardiac form of CD.

Intra-Discrete Typing Unit TcV Genetic Variability of Trypanosoma cruzi in Chronic Chagas' Disease Bolivian Immigrant Patients in Barcelona, Spain

Background: Trypanosoma cruzi has a high rate of biological and genetic variability, and its population structure is divided into seven distinct genetic groups (TcI-TcVI and Tcbat). Due to immigration, Chagas disease (ChD), caused by T. cruzi, has become a serious global health problem including in Europe. Therefore, the aim of this study was to evaluate the existence of genetic variability within discrete typing unit (DTU) TcV of T. cruzi in Bolivian patients with chronic ChD residing in Barcelona, Spain. Methods: The DNA was extracted from the peripheral blood of 27 patients infected with T. cruzi DTU TcV and the fragments of the genetic material were amplificated through the low stringency single primer-polymerase chain reaction (LSSP-PCR). The data generated after amplification were submitted to bioinformatics analysis. Results: Of the 27 patients evaluated in the study, 8/27 (29.6%) were male and 19/27 (70.4%) female, 17/27 (62.9%) were previously classified with the indeterminate clinical form of Chagas disease and 10/27 (37.1%) with Chagas cardiomyopathy. The LSSP-PCR detected 432 band fragments from 80 to 1,500 bp. The unweighted pair-group method analysis and principal coordinated analysis data demonstrated the existence of three distinct genetic groups with moderate-high rates of intraspecific genetic variability/diversity that had shared parasite's alleles in patients with the indeterminate and cardiomyopathy forms of ChD. Conclusions: This study demonstrated the existence of a moderate to high rate of intra-DTU TcV variability in T. cruzi. Certain alleles of the parasite were associated with the absence of clinical manifestations in patients harboring the indeterminate form of ChD. These results support the need to search for increasingly specific targets in the genome of T. cruzi to be correlated with its main biological properties and clinical features in patients with chronic ChD.

Genomic medicine in Chagas disease

Genetic approaches have been proposed for improving the understanding of the causes of differential susceptibility to Trypanosoma cruzi infection and Chagas disease outcome. Polymorphisms in genes involved in the immune/inflammatory response are being studied in order to clarify their possible role in the occurrence or severity of the cardiac and/or gastrointestinal complications. However still today, the number of significant associated genes is limited and the pathophysiological mechanisms underlying this condition are unknown. This article review the information currently available from the published scientific literature regarding the genetic variants of molecules of the immune system and other variants that can contribute to the clinical presentation of the disease. Genomic medicine will improve our knowledge about the molecular basis of Chagas disease, will open new avenues for developing biomarkers of disease progression, new therapeutic strategies to suit the requirements of individual patients, and will contribute to the control of one of the infections with the greatest socio-economic impact in the Americas.