Prenatal diagnosis of the isodicentric chromosome 22 associated with cat eye syndrome by multiplex ligation-dependent probe amplification

Cat eye syndrome (CES) is a very rare chromosomal syndrome characterized by various malformations such as anal atresia, preauricular malformation, coloboma of the iris, and congenial heart and renal defects. This genetic disorder is caused by partial duplication of chromosome 22, mostly as a result of a supernumerary isodicentric marker chromosome idic(22)(q11.2). Various congenital abnormalities and extreme phenotypic variability in CES patients have been reported, which have made prenatal diagnosis of CES difficult. We report the first case diagnosed with CES prenatally by multiplex ligation-dependent probe amplification in a woman who was referred to our hospital, for a fetus presenting with heart anomaly.

Chromosome identification in the Andean common bean accession G19833 (Phaseolus vulgaris L, Fabaceae)

Characterization of all chromosomes of the Andean G19833 bean genotype was carried out by fluorescent in situ hybridization. Eleven single-copy genomic sequences, one for each chromosome, two BACs containing subtelomeric and pericentromeric repeats and the 5S and 45S ribosomal DNA (rDNA) were used as probes. Comparison to the Mesoamerican accession BAT93 showed little divergence, except for additional 45S rDNA sites in four chromosome pairs. Altogether, the results indicated a relative karyotypic stability during the evolution of the Andean and Mesoamerican gene pools of P. vulgaris.

Cytotaxonomy and karyoevolution of the genus Crenicichla (Perciformes, Cichlidae)

Karyotypes of six cichlid species of the genus Crenicichla were investigated. The species C. cincta, C. inpa, C. reticulata, C. lugubris, and C. cf. johanna were collected from Amazon basin, and C. britskii was collected from the Paraná-Paraguai basin. All of the analysed species showed 2n = 48 chromosomes; however, C. cincta, C. lugubris, C. cf. johanna, and C. britskii had a karyotype formula of 8M-SM+40ST-A, FN = 56, while C. inpa and C. reticulata exhibited the formula 6M-SM+42ST-A, FN = 54. Analysis of active Ag-NORs revealed two NOR-bearing chromosomes in all species; however, theses cistrons were located on different chromosome pairs and/or in different chromosome locations in each species. This condition bears evolutionary significance, since it is the main chromosome marker of the process of karyotypic evolution among the species of the genus Crenicichla. In general, C-banding revealed a similar constitutive heterochromatin pattern in all species, although it was possible to detect some features that led us to infer that Crenicichla also presents a species-specific heterochromatin pattern.