Tetrasomy 18p syndrome (Online Mendelian Inheritance in Man 614290) is a very rare chromosomal disorder that is caused by the presence of isochromosome 18p, which is a supernumerary marker composed ...of two copies of the p arm of chromosome 18. Most tetrasomy 18p cases are de novo cases; however, familial cases have also been reported. It is characterized mainly by developmental delays, cognitive impairment, hypotonia, typical dysmorphic features, and other anomalies. Herein, we report de novo tetrasomy 18p in a 9-month-old boy with dysmorphic features, microcephaly, growth delay, hypotonia, and cerebellar and renal malformations. We compared our case with previously reported ones in the literature. Clinicians should consider tetrasomy 18p in any individual with dysmorphic features and cardiac, skeletal, and renal abnormalities. To the best of our knowledge, we report for the first time an association of this syndrome with partial agenesis of cerebellar vermis. Keywords: tetrasomy 18p, chromosomal, isochromosome, 18p, dysmorphic, CGH microarray, chromosome, syndrome
La técnica de Microarray cromosómico (CMA) es un estudio molecular de hibridación genómica comparativa, que detecta pérdidas y ganancias de regiones clínicamente significativas del genoma humano. El ...objetivo de esta presentación es describir las alteraciones en el número de copias (CNVs) clasificadas como patogénicas y probablemente patogénicas, detectadas con la técnica de CMA en el análisis de pacientes con discapacidad intelectual (DI) y/o anomalías congénitas. Para la detección de CNVs, se utilizó el test del Kleberg Cytogenetics Laboratory del Baylor College of Medicine, utilizando los slides v60K, v8.1.1.4x180K, v8.3.2x400K+SNPs. Dentro de las CNVs patogénicas y probablemente patogénicas observadas, se hallaron tanto variantes asociadas a síndromes de microdeleción o microduplicación conocidos como el Síndrome de Di George, Smith Magenis y Kleefstra, entre otros, como variantes claramente patogénicas aunque no asociadas a ningún síndrome conocido hasta la fecha. También se identificaron al menos dos alteraciones en un mismo paciente, constituyendo derivados cromosómicos o rearreglos complejos dentro del mismo cromosoma y ganancias o pérdidas que permitieron identificar y caracterizar cromosomas marcadores evidenciados en estudios citogenéticos previos. El estudio de CMA permitió caracterizar la alteración molecular causante del fenotipo y establecer el diagnóstico en pacientes con DI y/o anomalías congénitas, lográndose el correcto asesoramiento genético de las familias implicadas.
Ancistrus is a highly diverse neotropical fish genus that exhibits extensive chromosomal variability, encompassing karyotypic morphology, diploid chromosome number (2n = 34–54), and the evolution of ...various types of sex chromosome systems. Robertsonian rearrangements related to unstable chromosomal sites are here described. Here, the karyotypes of two Ancistrus species were comparatively analyzed using classical cytogenetic techniques, in addition to isolation, cloning, sequencing, molecular characterization, and fluorescence in situ hybridization of repetitive sequences (i.e., 18S and 5S rDNA; U1, U2, and U5 snDNA; and telomere sequences). The species analyzed here have different karyotypes: Ancistrus sp. 1 (2n = 38, XX/XY) and Ancistrus cirrhosus (2n = 34, no heteromorphic sex chromosomes). Comparative mapping showed different organizations for the analyzed repetitive sequences: 18S and U1 sequences occurred in a single site in all populations of the analyzed species, while 5S and U2 sequences could occur in single or multiple sites. A sequencing analysis confirmed the identities of the U1, U2, and U5 snDNA sequences. Additionally, a syntenic condition for U2-U5 snDNA was found in Ancistrus. In a comparative analysis, the sequences of rDNA and U snDNA showed inter- and intraspecific chromosomal diversification. The occurrence of Robertsonian rearrangements and other dispersal mechanisms of repetitive sequences are discussed.
The present Special Issue refers to the last 30 years of contributions to the application of cytogenetics to domestic animals, as clearly reported in the five-paper review. In addition, eight ...original contributions regarding the cytogenetics of several animal species are included. In each contribution, several thematic areas and various cytogenetic techniques are proposed to better demonstrate the potentiality of this biological technology in the genetic improvement of livestock. Special attention was paid to the presence of chromosomal abnormalities in domestic animals and their effects on reproduction, suggesting the routine use of karyotype analyses on reproducers to drastically reduce the effects on reproduction and the economic losses encountered by breeders. In addition to classical cytogenetic analyses such as chromosome banding, the use of molecular cytogenetics, especially the FISH mapping technique, with both specific molecular markers (generally BAC clones) and chromosome painting probes were emphasized in all papers to better study the following: (a) Chromosomal abnormalities; (b) The chromosomal evolution of species; (c) Physical gene mapping in light of genomic sequences in the most important domestic species. Finally, a specific review is dedicated to molecular cytogenetics, in which examples of applied molecular techniques, including the FISH technique, comparative genomic hybridization array, and PCR-based method, are reported.
Scleropages formosus (Osteoglossiformes, Teleostei) represents one of the most valued ornamental fishes, yet it is critically endangered due to overexploitation and habitat destruction. This species ...encompasses three major color groups that naturally occur in allopatric populations, but the evolutionary and taxonomic relationships of S. formosus color varieties remain uncertain. Here, we utilized a range of molecular cytogenetic techniques to characterize the karyotypes of five S. formosus color phenotypes, which correspond to naturally occurring variants: the red ones (Super Red); the golden ones (Golden Crossback and Highback Golden); the green ones (Asian Green and Yellow Tail Silver). Additionally, we describe the satellitome of S. formosus (Highback Golden) by applying a high-throughput sequencing technology. All color phenotypes possessed the same karyotype structure 2n = 50 (8m/sm + 42st/a) and distribution of SatDNAs, but different chromosomal locations of rDNAs, which were involved in a chromosome size polymorphism. Our results show indications of population genetic structure and microstructure differences in karyotypes of the color phenotypes. However, the findings do not clearly back up the hypothesis that there are discrete lineages or evolutionary units among the color phenotypes of S. formosus, but another case of interspecific chromosome stasis cannot be excluded.
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