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Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern.

Colorectal cancer (CRC) is a prevalent tumour throughout the world. CRC symptoms appear only in advanced stages causing decrease in survival of patients. Therefore, it is necessary to establish new strategies to detect CRC through subclinical screening. Genetic alterations and differential expression of genes that codify histone methyltransferases (HMTs) are linked to tumourigenesis of CRC. One important group of genes that codify HMTs are the NSD family composed of NSD1, NSD2 and NSD3 genes. This family participates in several cancer processes as oncogenes, harbouring several genetic alterations and presenting differential expression in tumour cells. To investigate the implications of NSD genes in CRC cancer, we described the genomic landscape of all NSD family members in a cohort of CRC patients from publicly available cancer datasets. We identified associations among recurrent copy number alterations (CNAs), mutations and differential gene expression concerning clinical outcome. We found in CRC repositories that NSD1 harbours a missense mutation in SET domain-the catalytic region-that probably could decrease its activity. In addition, we found an association between the low expressions of NSD1 and NSD2 and decrease of survival probability in CRC patients. Finally, we reported that NSD3 showed the highest rate of gene amplification, which was highly correlated to its mRNA expression, a common feature of many cancer drivers. Our results highlight the potential use of the NSD1 and NSD2 gene as prognostic markers of poor prognosis in CRC patients. Additionally, we appointed the use of the NSD3 gene as a putative cancer driver gene in CRC given that this gene harbours the highest rate of genetic amplification. All our findings are leading to novel strategies to predict and control CRC, however, some studies need to be conducted to validate these findings.

Botrytis cinerea Pers. is a necrotrophic and polyphageous pathogen economically important on soft fruits and crops producing severe agricultural losses. The Chilean strawberry, Fragaria chiloensis (L.) P. Mill. is one of the wild parents of commercial strawberry and has the capacity to tolerate the infection from the pathogenic fungus. A study was performed to make a genetic analysis of wild and cultivated individuals collected from three different regions of Central South Chile and compare the Botrytis infection performance. The dominant ISSR markers were used to generate the genetic fingerprinting and the native samples were contrasted against the commercial Fragaria × ananassa Duch. The samples from Contulmo presented the lowest diversity within population and the highest diversity between populations, but at the same time showed the highest tolerance to Botrytis infection. Infected leaves and fruits from F. × ananassa showed 3.6% of the area covered by the fungus, three days after inoculation, while the plants from Contulmo showed 3.3% of the area covered by the pathogen, five days after inoculation. The plants from Contulmo were classified as highly tolerant (HT), tolerant (T), moderately tolerant (MT), and susceptible (S) where 50% of plants belonged to the group of tolerant. The results, highly significant (p ≤ 0.01), indicate that the samples of F. chiloensis from Contulmo are more genetically homogeneous and can be classified as tolerant to the infection by Botrytis cinerea.Additional key words: grey mould, native strawberry, resistance. ResumenDiversidad genética en frutilla chilena (Fragaria chiloensis): respuesta diferencial a la infección con Botrytis cinerea Botrytis cinerea Pers. es un patógeno necrótrofo y polífago de importancia económica en cultivos y frutales, ocasionando importantes pérdidas en agricultura. La frutilla chilena, Fragaria chiloensis (L.) P. Mill., antecesor silvestre de la frutilla comercial, tiene la capacidad de tolerar la infección de una serie de hongos patogénicos. En este estudio se efectuó un análisis genético de plantas de frutilla chilena silvestres y cultivadas, recolectadas en tres diferentes regiones de la zona centro sur de Chile, en cuanto a su comportamiento frente a la infección de Botrytis. Los marcadores dominantes ISSR fueron utilizados para generar el patrón genética y las muestras de frutilla chilena fueron comparadas con las de Fragaria × ananassa Duch. Las muestras de Contulmo mostraron la más baja diversidad dentro de la población y la mayor entre poblaciones. Al mismo tiempo presentaron la mayor tolerancia a la infección con Botrytis. Las hojas y frutos de F. × ananassa, mostraron, tres días después de la inoculación, un 3,6% de su área cubierta por el patógeno. Por el contrario en las plantas recolectadas en Contulmo la infección fue más lenta, observándose un 3,3% del área cubierta por el patógeno, cinco días después de la inoculación. Las plantas de Contulmo fueron clasificadas como altamente tolerantes, tolerantes, moderadamente tolerantes y...

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