Article 1 - opinion
CRISPR/Cas 9: BIOETHICAL REFLECTIONS ON GENOME MODIFICATIONS
CRISPR/CAS9: REFLEXIONES BIOÉTICAS SOBRE LAS MODIFICACIONES GENÓMICAS
CRISPR/Cas9 can be considered the biotechnogical discovery of the century. Recent publications on the feasability of producing permanent changes in the DNA of gametes and embryos -changes that, in modifying the germinal line, can be inherited throughout generations- has renovated the interest for the ethical reflection around the impact of the new and not so new technologies. The first reactions rapidly occurred, from a request for the complete suspension of clinical application (that is, the prohibition of implanting a genetically modified embryo with CRISP in the uterus) till the approval of certainlines of basic research with similarly great preventions. This technology, characterized as “disruptive”, is analyzed at the light of the social phenomenon which has been generated around ethical, political, social, medical and subjective issues.
Key words: genetic edition, DNA changes, human genome
ARTÍCLE 2 - research
CLINICAL AND CYTOGENETIC CHARACTERIZATION OF A PATIENT WITH TETRASOMY 18p
CARACTERIZACIÓN CLÍNICA Y CITOGENÉTICA DE UN PACIENTE CON TETRASOMÍA 18p
Vazquez Cantu D.L., Gutiérrez García V.M., Cruz Camino H., Lara Díaz V.J., Garza García K., Garduño L.M., Meléndez R., Paz A., Mayén D.G., Cantú Reyna C.
The 18p tetrasomy is a structural chromosomal abnormality with the presence of an extra isochromosome 18p, caused by a nondisjunction failure during maternal meiosis II. This additional i(18p) occurs in 1 of 180,000 live-born children worldwide, and affects males and females equally. It is characterized by craniofacial dysmorphisms; ears, nose and throat (ENT) abnormalities; musculoskeletal alterations; and global development delay. We aim to present the clinical and cytogenetic findings of a 3-year-10-month-old Latin American male with i(18p), to support the gene dosage effects, comparing his features with the ones reported in literature. This patient was product of the second pregnancy of a 39-year-old woman and the first son of a 49-year-old man. His main clinical features were microcephaly, facial dysmorphism, generalized hypotonia, and developmental delay. A blood sample of the patient was required to perform a GTG-banded karyotype and a fluorescence in situ hybridization (FISH) for chromosome 18 short arm. In addition, an SNP microarray analysis was carried out to detect genomic imbalances. Cytogenetic analysis revealed the presence of a metacentric supernumerary marker chromosome. The FISH study confirmed the origin of the marker chromosome by showing two signals for the 18p subtelomere and an intermediate signal for the 18 centromere. The microarray analysis showed a copy number gain of 18,385 Mb within the 18p.Tetrasomy tends to be a result of de novo events. The presence of the patient’s isochromosome could be explained by advanced maternal age as it is known that this factor has high influence in isochromosome formation. Despite that there were no genes associated with the i(18p)’s clinical manifestations, these features are negatively correlated with dosage effects of the entire short arm. Physical and language therapy was recommended to the patient; the family received medical orientation, and awareness in family planning was raised.
Key words: tetrasomy 18p, chromosome 18, isochromosome, cytogenetic analysis, case report
ARTÍCLE 3 - research
GENETIC ARCHITECTURE AS AN ANALYSIS TOOL OF THE GENOTYPE-PHENOTYPE MAP
LA ARQUITECTURA GENÉTICA COMO HERRAMIENTA DE ANÁLISIS DEL MAPA GENOTIPO-FENOTIPO
Petino Zappala M.A., Fanara J.J.
Studying the relationship between genotype and phenotype is of great importance for genetics and life science studies in general. In contrast with the traditional view of this relationship as an invariant set of parameters, the current approach incorporates the concept of genetic architecture, a realistic and dynamic tool that allows to elucidate the genotype-phenotype map, which is now regarded as an evolving structure. From the complex relationships between the elements in the genotype-phenotype map several emergent properties arise that can explain different evolutionary phenomena. Moreover, some of these properties promote the accumulation of genetic variability in natural populations, which constitutes the substrate to evolutionary processes such as natural selection. The characterization and analysis of the genetic architecture of adaptive traits constitutes a powerful tool to understand the genetics underpinnings of evolution.
Key words: plasticity, canalization, modularity, cryptic genetic variability, evolvability
ARTÍCLE 4 - research
FALSE DISCOVERY RATE CONTROL IN ASSOCIATION MAPPING WITH GENETICALLY STRUCTURED POPULATIONS
CONTROL DE FALSOS DESCUBRIMIENTOS EN MAPEO ASOCIATIVO CON POBLACIONES ESTRUCTURADAS
Peña Malavera A., Bruno C., Balzarini M.
The association tests between molecular markers and phenotypic traits are crucial for the Quantitative Trait Loci (QTL) identification. Biotechnological advances increased the molecular marker information; consequently, the number of genotype-phenotype association tests required incremented too. The multiple statistical inferences (multiplicity) demand corrections of the p-values obtained for each comparison in order to keep limited the error rates for the family of association tests. However, classic statistical correction methods such as Bonferroni, False Discovery Rate (FDR) and the Effective Number of Independent Test (Meff) were developed in the context of independent data. Wherever, when the population genetic structure is present, the data are no longer independent. In this paper, we propose a method of correction for multiplicity based on estimation of the effective number of tests from a model that adjust for the underlying correlation structure. We evaluate the performance of the proposed procedure in the estimation of p-values for a set of simulated QTL. The results suggest that the proposed method provides control of FDR and has more power than other methods for multiplicity correction used in association mapping.
Key words: multiplicity, association studies, effective number of hypothesis test, linear models.
ARTÍCLE 5 - research
DOES THE HARDY-WEINBERG LAW OF EQUILIBRIUM WORK IN AUTOPOLYPLOIDS AS IT DOES IN DIPLOIDS?
¿FUNCIONA LA LEY DE EQUILIBRIO DE HARDY-WEINBERG EN AUTOPOLIPLOIDES IGUAL QUE EN DIPLOIDES?
The law of equilibrium Hardy-Weinberg is the cornerstone of the population genetics and of the quantitative genetics; however, for its calculation in autopolyploids it is necessary take in account that the allelic and gametic frequencies are different, contrary to the diploids where they are the same. This causes that the calculations must be done with the allelic frequencies or gametic based on allelic frequencies. Otherwise the equilibrium is broken in the population and the bias that this entails in the calculation of other genetical test like Wright’s F statistics, the Nei’s GST or Bayesian models that are based on the disequilibrium that populations show. That is why in this work they developed models of one locus with two alleles in autotetraploid and autooctoploid genotypes to make a generalization of the law of equilibrium in autopolyploid populations.
Key words: Population Genetics, Quantitative Genetics, Genotype frequencies calculation
COMMUNICATION 6 - research
CHILEAN PLANTS CYTOGENETIC DATABASE: COVERAGE, FEATURES AND USAGES
BASE DE DATOS CITOGENÉTICOS DE PLANTAS CHILENAS: COBERTURA, CARACTERÍSTICAS Y USOS
Jara-Seguel P., Urrutia J.
Chilean Plants Cytogenetic Database (CPCD) is a resource available on line in electronic format, which provides a cytogenetics catalogue for continental and insular Chilean vascular plants. In this report, we made reference to the CPCD, discussing aspects on its coverage, features and usages. Currently, the database stores cytogenetic information for 247 species, 107 genera, and 55 families belonging to Pteridophyta, Pinophyta, and Magnoliophyta.
Key words: chromosome number, karyotype, Chilean Plants
DR. EDUARDO E. CASTILLA