No abstract

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.

No abstract

Se dá a conocer el catálogo de los pteridófitos actualmente reconocidos en la región de Valencia (España); especificando su distribución en las cuadriculas del retículo U.T.M.

Mitotic chromosome numbers are reported from 16 Hieracium and two Pilosella species from the Iberian Peninsula and the Balearic Islands that are little known cytogenetically. The chromosome numbers of Hieracium aragonense Scheele (2 n = 27, 36), H. compositum Lapeyr. (2 n = 27), H. murcandidum G. Mateo (2 n = 27), H. spathulatum Scheele (2 n = 27), H. segurae Mateo (2 n = 27), H. teruelanum Mateo (2 n = 27), H. valentinum Pau (2 n = 27), Pilosella pseudovahlii (De Retz) Mateo (2 n = 18), and P. tardans (Peter) Sójak (2 n = 36) were determined for the first time. New cytotypes were detected in H. cordifolium Lapeyr. (2 n = 27) and H. loscosianum Scheele (2 n = 36). The karyotype of the studied species was similar in overall morphology and comprised metacentric and submetacentric chromosomes; secondary constrictions (up to two) were detected in the chromosome complements of some species.