Reduced penetrance in human inherited disease

For many inherited diseases, the same mutation is not always expressed in all persons who care it, moreover, when the mutation is expressed, it is not always expressed in the same way. These findings are the basis for the concepts of penetrance and expressivity. Understanding the factors that control penetrance of disease genes will provide insight into the fundamental disease processes and will help in genetic counselling. With the advancement of molecular genetics over the last few years, some of the underlying mechanisms of reduced penetrance have been elucidated. These include, mutation type, allelic variations in gene expression, epigenetic factors, gene-environment interplay, influence of age and sex, allele dosage, oligogenic and modifier genes, copy number variations as well as the influence of additional gene variants and the effect of single nucleotide polymorphisms. The aim of this review is to clarify factors affecting gene penetrance as well as some of the underlying molecular mechanisms in some genetic disorders

La biotecnología como herramienta para la propagación, conservación y el mejoramiento genético del guayabo / Biotechnology as a tool for propagation, con-servation and genetic breeding in guava

Las técnicas biotecnológicas contribuyen positiva y significativamente en los programas de propagación, conservación y mejoramiento de las especies vegetales. Dentro de éstas, el cultivo de tejidos, el desarrollo de mapas de ligamientos genéticos y de QTLs y la detección de genes de interés han demostrado ser de gran utilidad para los mencionados propósitos. En este sentido, se estandarizó una técnica para la multiplicación in vitro de la forma silvestre de guayabo en tres fases de cultivo: establecimiento, multiplicación de propágulos y enraizamiento. La misma constituye una vía de utilidad para la propagación, la conservación de germoplasma y el mejoramiento genético en la especie. Además, se estandarizó un método de conservación a corto-mediano plazo. Por otra parte, se construyó un mapa de ligamiento genético para la especie empleando marcadores AFLP y SSR. Los 11 grupos del mapa de ligamiento genético y los 50 QTLs relacionados con caracteres vegetativos y de calidad interna y externa del fruto, constituyen el punto de partida para el clonaje de genes de interés agrícola y la implementación futura de la selección asistida por marcadores en el guayabo. De igual forma, las 176 secuencias candidatas a genes de resistencia (RGL) y del desarrollo de la planta (MADS-box y HOMEO-box) detectadas pueden ser de gran utilidad en la saturación del mapa de ligamiento referido, el estudio de la variabilidad presente en el cultivo, así como en la solución de problemas relacionados con el rendimiento, la producción y la resistencia a estrés biótico y abiótico

Biotechnologies contribute positively and signifi¬cantly in the propagation, conservation and breeding programs of many plant species. From them, tissue culture, linkage maps and QTLs detection for interesting genes have been proved to be of great utility for these purposes. In this sense, a technique for in vitro multiplication of wild guava was standardized in three culture phases: establishment, multiplication and rooting. This technique constituted a useful way for propagation, germplasm conservation and genetic breeding in the specie. A method for short-medium term conservation was also standardized. On the other hand, a genetic linkage map was constructed for the specie using AFLP and SSR markers. The 11 groups of the genetic linkage map and the 50 QTLs related with vegetative and internal/external fruit characters constitute the starting point for genes cloning of agricultural interest and the future imple¬mentation of markers assisted selection in guava. Also, the 176 candidate sequences for resistance-gene-like (RGL) and plant development (MADS-box and HOMEO-box) genes detected can be of great utility in linkage map saturation, variability studies in this crop, as well as in the solution of problems rela¬ted with yielding and resistance to biotic and abiotic stresses.

Association of CFTR gene mutation with bronchial asthma.

Mutation on both the copies of cystic fibrosis transmembrane conductance regulator (CFTR) gene results in cystic fibrosis (CF), which is a recessively transmitted genetic disorder. It is hypothesized that individuals heterozygous for CFTR gene mutation may develop obstructive pulmonary diseases like asthma. There is great heterogeneity in the phenotypic presentation and severity of CF lung disease. This could be due to genetic or environmental factors. Several modifier genes have been identified which may directly or indirectly interact with CFTR pathway and affect the severity of disease. This review article discusses the information related to the association of CFTR gene mutation with asthma. Association between CFTR gene mutation and asthma is still unclear. Report ranges from studies showing positive or protective association to those showing no association. Therefore, studies with sufficiently large sample size and detailed phenotype are required to define the potential contribution of CFTR in the pathogenesis of asthma.

Genetic variability and interrelationships of mainly quantitative traits in Glycyrrhiza uralensis cultivated population / 中国中药杂志

<p><b>OBJECTIVE</b>The main aim of the research was to evaluate genetic variability and interrelationships of mainly quantitative traits in 2-year population, and provide a basis for high-yield breeding of Glycyrrhiza uralensis.</p><p><b>METHOD</b>Four genotype G. uralensis population were transplanting in four different environment using complete randomized block design with three replication, and the 10 quantitative traits, including plant height (PH), stem diameter (SD), tiller number (TN), taproot length (TRL), root length (RL), root diameter (RD), diameter of 20 cm below the root head (D20), taperingness (TR), lateral root number (LRN) and root fresh weight (RFW) were measured in field.</p><p><b>RESULT</b>The difference among population for all evaluated traits were significant (P<0.05) through Duncan's multiple range tests, and the coefficient of variation of RFW and LRN were above 25%. The analysis of variance was used to evaluate the traits of four populations across to four different environment Genotype, environment and their interaction effect were significant (P<0.05) or highly significant (P<0.01) for mainly evaluated traits. Simple correlation between traits showed that PH, SD, LRN, RL, RD and D20 had highly significant (P<0.01) and positive correlation with RFW. Results of the path coefficient analyses showed that D20 had the greatest positive direct effect on RFW, followed by the traits of PH and RL.</p><p><b>CONCLUSION</b>Selection for increased D20, RL and PH would be the best indirect selection traits for increasing root yield. Meanwhile, ample genetic variability exists in the G. uralensis 2-year population, it could be used for breeding improvement of root yield.</p>