Complex evolutionary pathways of the intergenic region of the mini-exon gene in Trypanosoma cruzi TcI: a possible ancient origin in the Gran Chaco and lack of strict genetic structuration.

The TcI discrete typing unit (DTU) of Trypanosoma cruzi is the most abundant and widely spread in the Americas. It is found in a wide range of triatomine and mammal species, which are distributed throughout the Americas in sylvatic and domestic environments. Previous studies based on intergenic sequences of the mini-exon gene (SL-IR) have identified five genotype groups within TcI. Based in the large number of sequences available in GenBank, the present study conducted an exhaustive revision of the sequence variability of the SL-IR within TcI using 244 sequences from isolates, cellular or molecular clones, from 11 Latin American countries. First, the evolutionary branching between strains was examined by analyzing only the single nucleotide polymorphism (SNP) deleting the microsatellite region and the gaps from the total alignment. Then the variability of the microsatellite region was re-analyzed alone using principal component analysis (PCA). After haplotype reconstruction using the PHASE algorithm, because of the presence of several ambiguous nucleotides in the SNP region, a total of 131 different haplotypes were obtained. The topology reveals how difficult it is to identify an obvious structure in TcI for most of the parameters examined. Somewhat genetic and geographical structures exist, but no structure was depicted with cycle and host origins. Indeed, the long-lasting evolution with possible recombination events, the occurrence of several waves of geographical dispersions (old and recent), and the high flow of strains between sylvatic and domestic cycles partially hide the major evolutionary trends within TcI. Moreover, we identified several problems in previous analyses, and concluded that in absence of supplementary studies of TcI phylogeny with other genetic markers, it is hazardous to use only the mini-exon intergenic region as a relevant marker of the substructure within TcI.

Sequence analysis of the spliced-leader intergenic region (SL-IR) and random amplified polymorphic DNA (RAPD) of Trypanosoma rangeli strains isolated from Rhodnius ecuadoriensis, R. colombiensis, R. pallescens and R. prolixus suggests a degree of co-evolution between parasites and vectors.

Spliced leader intergenic region (SL-IR) sequences from 23 Trypanosoma rangeli strains isolated from the salivary glands of Rhodnius colombiensis, R. ecuadoriensis, R. pallescens and R. prolixus and two human strains revealed the existence of 4 genotypes with CA, GT, TA, ATT and GTAT microsatellite repeats and the presence of insertions/deletions (INDEL) and single nucleotide polymorphism (SNP) characterizing each genotype. The strains isolated from the same vector species or the same Rhodnius evolutionary line presented the same genotypes, even in cases where strains had been isolated from vectors captured in geographically distant regions. The dendrogram constructed from the SL-IR sequences separated all of them into two main groups, one with the genotypes isolated from R. prolixus and the other group containing three well defined sub-groups with the genotypes isolated from R. pallescens, R. colombiensis and R. ecuadoriensis. Random amplified polymorphic DNA (RAPD) analysis showed the same two main groups and sub-groups supporting strict T. rangeli genotypes' association with Rhodnius species. Combined with other studies, these results suggest a possible co-evolutionary association between T. rangeli genotypes and their vectors.

[Validation of the Diagnostic Interview for Genetic Studies (DIGS) in Colombia]. / Validación de la entrevista diagnóstica para estudios genéticos (DIGS) en Colombia.

An interview tool, Diagnostic Interview for Genetic Studies (DIGS 3.0), was translated into Spanish for application in studies of psychiatric disorders in Colombia. Two Spanish translations of the original English version of DIGS were prepared and back-translated into English. A review committee verified the linguistic and cultural equivalence of the translations. The evaluator and test-retest reliability were assessed calculating Cohen's kappa for samples of 65 and 91 patients respectively. DIGS proved valid in both appearance and content. The confidence interval (C.I.) was excellent for schizophrenia (kappa = 0.81, C.I. 95% = 0.68-0.93), bipolar disorder (kappa = 0.87, C.I. 95% = 0.75-0.99), major depressive disorder (kappa = 0.86, C.I. 95% = 0.70-1.00), and for a normal diagnosis (kappa = 0.65, C.I. 95% = 0.41-0.89); it was good for other psychiatric diagnosis (kappa = 0.65, C.I. 95% = 0.41-0.89) and poor for schizoaffective disorder (kappa = 0.37, C.I. 95% = -0.02-0.76). Test-retest reliability was excellent for all diagnoses (kappa > 0.8), except for "other psychiatric diagnoses" (kappa = 0.64, C.I. 95% = 0.31-0.96). The Spanish translation of the DIGS was comprehensible, with face and content validity, and good test-retest and evaluator reliability. This translation will be a useful tool for genetic studies of psychiatric disorders in Latin America, particularly where schizophrenia and affective disorders are involved.

Validación de la entrevista diagnóstica para estudios genéticos (DIGS) en Colombia / Validation of the Diagnostic Interview for Genetic Studies (DIGS) in Colombia

Objetivo: validar la entrevista diagnóstica para estudios genéticos (DIGS 3.0) en Colombia. Métodos: se hicieron dos traducciones del inglés al español del DIGS y se hizo traducción en sentido inverso (al inglés) de cada una. Un comité de revisión verificó la equivalencia translingüística y transcultural. Se evaluó la confiabilidad examen-reexamen e interevaluador del DIGS 3.0 en 65 y 91 pacientes, respectivamente, mediante el cálculo de kappa de Cohen. Resultados: el DIGS 3.0 mostró ser comprensible, con validez de apariencia y de contenido. La confiabilidad interevaluador fue excelente para esquizofrenia (kapa=0,81, IC95%: 0,68-0,93), trastorno bipolar (kapa=0,87, IC95%: 0,75-0,99), trastorno depresivo mayor (kapa=0,86, IC95%: 0,7- 1) y ausencia de trastorno psiquiátrico (kapa=0,88, IC95%: 0,71-1); fue buena para otro diagnóstico psiquiátrico (kapa=0,65, IC95%: 0,41-0,89) y pobre para trastorno esquizoafectivo (kapa=0,37, IC95%: -0,02-0,76). La confiabilidad examen-reexamen fue excelente para todos los diagnósticos (kapa>0,8), excepto para otro diagnóstico psiquiátrico (kapa=0,64, IC95%: 0,31-0,96), donde fue buena. Conclusiones: la versión en español del DIGS para Colombia mostró comprensibilidad, validez de apariencia y de contenido, y confiabilidad examen-reexamen e interevaluador. Es una herramienta útil para estudios genéticos en esquizofrenia y en trastornos afectivos.

An interview tool, Diagnostic Interview for Genetic Studies (DIGS 3.0), was translated into Spanish for application in studies of psychiatric disorders in Colombia. Two Spanish translations of the original English version of DIGS were prepared and backtranslated into English. A review committee verified the linguistic and cultural equivalence of the translations. The evaluator and test-retest reliability were assessed calculating Cohen’s kappa for samples of 65 and 91 patients respectively. DIGS proved valid in both appearance and content. The confidence interval (C.I.) was excellent for schizophrenia (kappa=0.81, C.I. 95% = 0.68-0.93), bipolar disorder (kappa=0.87, C.I. 95% = 0.75-0.99), major depressive disorder (kappa=0.86, C.I. 95% = 0.70-1.00), and for a normal diagnosis (kappa=0.65, C.I. 95% = 0.41-0.89); it was good for other psychiatric diagnosis (kappa=0.65, C.I. 95% = 0.41-0.89) and poor for schizoaffective disorder (kappa=0.37, C.I. 95% = -0.02-0.76). Test-retest reliability was excellent for all diagnoses (kappa>0.8), except for "other psychiatric diagnoses" (kappa=0.64, C.I. 95% = 0.31-0.96). The Spanish translation of the DIGS was comprehensible, with face and content validity, and good test-retest and evaluator reliability. This translation will be a useful tool for genetic studies of psychiatric disorders in Latin America, particularly where schizophrenia and affective disorders are involved.